Sodium and Potassium

References:

Nephrol Dial Transplant. 2004 May;19(5):1190-7.

Correction of metabolic acidosis improves thyroid and growth hormone axes in haemodialysis patients.
Wiederkehr MR, Kalogiros J, Krapf R.
Baylor University Medical Center, Dallas Nephrology Associates, 3500 Gaston Avenue, Dallas, TX 75246, USA.

BACKGROUND: Chronic metabolic acidosis (CMA) in normal adults results in complex endocrine and metabolic alterations including growth hormone (GH) insensitivity, hypothyroidism, hyperglucocorticoidism, hypoalbuminaemia and loss of protein stores. Similar alterations occur in chronic renal failure, a prototypical state of CMA. We evaluated whether metabolic acidosis contributes to the endocrine and metabolic alterations characteristic of end-stage renal disease. METHODS: We treated 14 chronic haemodialysis patients with daily oral Na-citrate for 4 weeks, yielding a steady-state pre-dialytic plasma bicarbonate concentration of 26.7 mmol/l, followed by 4 weeks of equimolar Na-chloride, yielding a steady-state pre-dialytic plasma bicarbonate of 20.2 mmol/l. RESULTS: Blood pressure, body weight and dialysis adequacy were equivalent in the two protocols. Na-citrate treatment corrected CMA, improved GH insensitivity, increased and normalized plasma free T(3) concentration, and improved plasma albumin. Correction of CMA had no significant effect on measured cytokines (interleukin-1beta and -6, tumour necrosis factor-alpha) or acute phase reactants (C-reactive protein, serum amyloid A, alpha(2)-macroglobulin). CONCLUSION: CMA contributes to the derangements of the growth and thyroid hormone axes and to hypoalbuminaemia, but is not a modulator of systemic inflammation in dialysis patients. Correcting CMA may improve nutritional and metabolic parameters and thus lower morbidity and mortality

Kidney Int. 2002 Dec;62(6):2160-6.
Bone histology and bone mineral density after correction of acidosis in distal renal tubular acidosis.
Domrongkitchaiporn S, Pongskul C, Sirikulchayanonta V, Stitchantrakul W, Leeprasert V, Ongphiphadhanakul B, Radinahamed P, Rajatanavin R.
Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.

BACKGROUND: The association between chronic metabolic acidosis and alterations in bone cell functions has been demonstrated in vitro and in animal studies. However, the causal role of acidosis and the effects of alkaline therapy on bone histology and bone mineral density in chronic metabolic acidosis have never been systematically demonstrated in humans. This study was conducted to examine the alterations in bone mineral density and bone histology before and after correction of acidosis among patients with distal renal tubular acidosis (dRTA) METHODS: Correction of metabolic acidosis by potassium citrate was done in non-azotemic dRTA patients, 6 females and 4 males, who had never received long-term alkaline therapy before enrolling into this study. Blood chemistries, serum intact parathyroid hormone, and 24-hour urine collection for the determination of urinary calcium, phosphate, sodium, potassium, bone mineral density determination, and transiliac bone biopsy were done in all patients at baseline and after one year of potassium citrate therapy. RESULTS: Significant elevations in serum bicarbonate (16.5 +/- 3.0 vs. 24.6 +/- 2.8 mEq/L, P < 0.05) and urinary potassium excretion (35.2 +/- 7.9 vs. 55.4 +/-3.5 mEq/L, P < 0.05) were observed after potassium citrate therapy. No significant alterations in other serum and urine electrolytes were found after the therapy. Serum intact parathyroid hormone level was also significantly elevated after one year of treatment (12.8 +/- 7.3 vs. 26.2 +/- 8.7 pg/mL, P < 0.05). Bone formation rate was significantly suppressed at baseline and was normalized by the treatment (0.02 +/- 0.02 vs. 0.06 +/- 0.03 microm(3)/microm(2)/day, P < 0.05). There were non-significant elevations in trabecular bone volume, osteoblastic and osteoclastic numbers. Bone mineral densities in dRTA patients were also significantly decreased below normal values in most studied areas at baseline and were significantly elevated at the trochanter of femur (0.677 +/- 0.136 vs. 0.748 +/- 0.144 g/c m(2), P < 0.05) and total femur (0.898 +/- 0.166 vs. 0.976 +/- 0.154 g/c m(2), P < 0.05) after the treatment. CONCLUSIONS: This study demonstrates that alkaline therapy corrects abnormal bone cell function and elevates bone mineral density in dRTA patients, indicating the causal role of acidosis in the alterations of bone cell functions and reduction in bone mineral density. Parathyroid gland activity also may be involved in the adaptation of the body to chronic metabolic acidosis.

DGHS Chron. 1985 Jan-Mar;21(1):1, 3.
Dehydration: W.H.O. has a new solution.

Ayres D.

PIP: The World Health Organization (WHO) has developed an improved formula for oral rehydration solution (ORS) that is based on trisodium citrate dihydrate rather than sodium bicarbonate. The new preparation will be easier and cheaper to package, have a longer shelf-life, and be more effective against diarrhea. Clinical trials have shown that the new formula corrects acidosis at a similar rate to sodium bicarbonate and is far more effective in reducing the amount of diarrhea, especially in diseases such as cholera. Although the citrate solution costs slightly more than the earlier preparation, packaging costs can be reduced by up to 50% through local production, making the end product cheaper. Local production of ORS-citrate does not require new investment or changes in equipment. WHO is recommending that countries with supplies of ORS-bicarbonate should use up these stocks and then decide whether to switch to the new formula. Research is also being carried out on other improved ORS formulas, e.g. glycine-fortified and rice powder-based ORS.

Eur J Nutr. 2001 Oct;40(5):200-13.

Diet, evolution and aging--the pathophysiologic effects of the post-agricultural inversion of the potassium-to-sodium and base-to-chloride ratios in the human diet.
Frassetto L, Morris RC Jr, Sellmeyer DE, Todd K, Sebastian A.
University of California, San Francisco 94143, USA.

Theoretically, we humans should be better adapted physiologically to the diet our ancestors were exposed to during millions of years of hominid evolution than to the diet we have been eating since the agricultural revolution a mere 10,000 years ago, and since industrialization only 200 years ago. Among the many health problems resulting from this mismatch between our genetically determined nutritional requirements and our current diet, some might be a consequence in part of the deficiency of potassium alkali salts (K-base), which are amply present in the plant foods that our ancestors ate in abundance, and the exchange of those salts for sodium chloride (NaCl), which has been incorporated copiously into the contemporary diet, which at the same time is meager in K-base-rich plant foods. Deficiency of K-base in the diet increases the net systemic acid load imposed by the diet. We know that clinically-recognized chronic metabolic acidosis has deleterious effects on the body, including growth retardation in children, decreased muscle and bone mass in adults, and kidney stone formation, and that correction of acidosis can ameliorate those conditions. Is it possible that a lifetime of eating diets that deliver evolutionarily superphysiologic loads of acid to the body contribute to the decrease in bone and muscle mass, and growth hormone secretion, which occur normally with age? That is, are contemporary humans suffering from the consequences of chronic, diet-induced low-grade systemic metabolic acidosis? Our group has shown that contemporary net acid-producing diets do indeed characteristically produce a low-grade systemic metabolic acidosis in otherwise healthy adult subjects, and that the degree of acidosis increases with age, in relation to the normally occurring age-related decline in renal functional capacity. We also found that neutralization of the diet net acid load with dietary supplements of potassium bicarbonate (KHCO3) improved calcium and phosphorus balances, reduced bone resorption rates, improved nitrogen balance, and mitigated the normally occurring age-related decline in growth hormone secretion--all without restricting dietary NaCl. Moreover, we found that co-administration of an alkalinizing salt of potassium (potassium citrate) with NaCl prevented NaCl from increasing urinary calcium excretion and bone resorption, as occurred with NaCl administration alone. Earlier studies estimated dietary acid load from the amount of animal protein in the diet, inasmuch as protein metabolism yields sulfuric acid as an end-product. In cross-cultural epidemiologic studies, Abelow found that hip fracture incidence in older women correlated with animal protein intake, and they suggested a causal relation to the acid load from protein. Those studies did not consider the effect of potential sources of base in the diet. We considered that estimating the net acid load of the diet (i. e., acid minus base) would require considering also the intake of plant foods, many of which are rich sources of K-base, or more precisely base precursors, substances like organic anions that the body metabolizes to bicarbonate. In following up the findings of Abelow et al., we found that plant food intake tended to be protective against hip fracture, and that hip fracture incidence among countries correlated inversely with the ratio of plant-to-animal food intake. These findings were confirmed in a more homogeneous population of white elderly women residents of the U.S. These findings support affirmative answers to the questions we asked above. Can we provide dietary guidelines for controlling dietary net acid loads to minimize or eliminate diet-induced and age-amplified chronic low-grade metabolic acidosis and its pathophysiological sequelae. We discuss the use of algorithms to predict the diet net acid and provide nutritionists and clinicians with relatively simple and reliable methods for determining and controlling the net acid load of the diet. A more difficult question is what level of acidosis is acceptable. We argue that any level of acidosis may be unacceptable from an evolutionarily perspective, and indeed, that a low-grade metabolic alkalosis may be the optimal acid-base state for humans.

Urol Res. 2001 Oct;29(5):295-302.
A comparison of the effects of potassium citrate and sodium bicarbonate in the alkalinization of urine in homozygous cystinuria.
Fjellstedt E, Denneberg T, Jeppsson JO, Tiselius HG.
Department of Internal Medicine, Motala Hospital, Sweden.

For many years, urine alkalinization has been one of the cornerstones in the treatment of homozygous cystinuria. Because of the relationship found between the excretion of urinary sodium and cystine, potassium citrate has emerged as the preferred sodium-free alkalizing agent. To evaluate the usefulness of potassium citrate for urine alkalization in cystinuric patients, sodium bicarbonate and potassium citrate were compared in 14 patients (10 on tiopronin treatment and four without treatment with sulfhydryl compounds). The study started with 1 week without the use of any alkalizing agents (Period 0) followed by 2 weeks with sodium bicarbonate (Period 1) and 2 weeks with potassium citrate (Period 2). Urinary pH, volume, excretion of sodium, potassium, citrate and free cystine, as well as the plasma potassium concentration, were recorded. Potassium citrate was shown to be effective as an alkalizing agent and, in this respect, not significantly different from sodium bicarbonate. Even though a normal diet was used, a significant increase in urinary sodium excretion was observed with sodium bicarbonate (Period 1). Urinary potassium and citrate excretion increased with potassium citrate (Period 2). A significant correlation was found between urinary sodium and cystine in the tio-pronin-treated patients. No significant differences in cystine excretion were recorded in Periods 0, 1 and 2. Plasma potassium was significantly higher during Period 2, but only one patient developed a mild hyperkalemia (5.0 mmol/l). The use of potassium citrate for urine alkalization in homozygous cystinuria is effective and can be recommended in the absence of severe renal impairment.

Am J Kidney Dis. 2001 Nov;38(5):979-87.
Simplified citrate anticoagulation for high-flux hemodialysis.
Apsner R, Buchmayer H, Lang T, Unver B, Speiser W, Sunder-Plassmann G, Horl WH.
Department of Internal Medicine III, Division of Nephrology and Dialysis, and Institute of Laboratory Medicine, General Hospital and Medical School of Vienna, Austria.

In a randomized crossover trial, we compared a simple citrate anticoagulation protocol for high-flux hemodialysis with standard anticoagulation by low-molecular-weight heparin (dalteparin). Primary end points were urea reduction rate (URR), Kt/V, and control of electrolyte and acid-base homeostasis. Secondary end points were bleeding time at vascular puncture sites and markers of activation of platelets, coagulation, and fibrinolysis. Solute removal during citrate dialysis was excellent (URR, 0.71 +/- 0.06; Kt/V, 1.55 +/- 0.3) and similar to results of conventional bicarbonate hemodialysis anticoagulation with dalteparin (URR, 0.72 +/- 0.04; Kt/V, 1.56 +/- 0.2). Electrolyte control was effective with both anticoagulation regimens, and total and ionized calcium, sodium, potassium, and phosphate concentrations at the end of dialysis did not differ. Alkalemia was less frequent after citrate than conventional dialysis (pH 7.5 in 25% versus 62% of patients; mean pH at end of dialysis, 7.46 +/- 0.06 versus 7.51 +/- 0.07; P < 0.01). Bleeding time at puncture sites was shorter by 30% after citrate compared with dalteparin anticoagulation (5.43 +/- 2.80 versus 7.86 +/- 2.93 minutes; P < 0.001). Activation of platelets, coagulation, and fibrinolysis was modest for both treatments and occurred mainly within the dialyzer during dalteparin treatment and in the vascular-access region during citrate anticoagulation. Citrate-related adverse events were not observed. We conclude that citrate anticoagulation for high-flux hemodialysis is feasible and safe using a simple infusion protocol.

Respir Care. 2001 Apr;46(4):354-65.

Metabolic alkalosis.
Khanna A, Kurtzman NA.
Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA.

Metabolic alkalosis is a primary pathophysiologic event characterized by the gain of bicarbonate or the loss of nonvolatile acid from extracellular fluid. The kidney preserves normal acid-base balance by two mechanisms: bicarbonate reclamation, mainly in the proximal tubule, and bicarbonate generation, predominantly in the distal nephron. Bicarbonate reclamation is mediated mainly by a Na(+)-H(+) antiporter and to a smaller extent by the H(+)-ATPase (adenosine triphosphate-ase). The principal factors affecting HCO3(-) reabsorption include effective arterial blood volume, glomerular filtration rate, chloride, and potassium. Bicarbonate regeneration is primarily affected by distal Na(+) delivery and reabsorption, aldosterone, arterial pH, and arterial partial pressure of carbon dioxide. To generate metabolic alkalosis, either a gain of base or a loss of acid must occur. The loss of acid may be via the gastrointestinal tract or via the kidney. Excess base may be gained by oral or parenteral HCO3(-) administration or by lactate, acetate, or citrate administration. Factors that help maintain metabolic alkalosis include decreased glomerular filtration rate, volume contraction, hypokalemia, hypochloremia, and aldosterone excess. Clinical states associated with metabolic alkalosis are vomiting, mineralocorticoid excess, the adrenogenital syndrome, licorice ingestion, diuretic administration, and Bartter's and Gitelman's syndromes. The effects of metabolic alkalosis on the body are variable and include effects on the central nervous system, myocardium, skeletal muscle, and liver. Treatment of this disorder is simple, once the pathophysiology of the cause is delineated. Therapy consists of reversing the contributory factors that are promoting the alkalosis and, in severe cases, administration of carbonic anhydrase inhibitors, acid infusion, and low bicarbonate dialysis.

J Am Diet Assoc. 1999 Dec;99(12):1536-41.

Alterations in taste thresholds in men with chronic obstructive pulmonary disease.
Chapman-Novakofski K, Brewer MS, Riskowski J, Burkowski C, Winter L.
Department of Food Science and Human Nutrition, University of Illinois, Urbana 61801, USA.

OBJECTIVE: Weight loss is a common occurrence in chronic obstructive pulmonary disease (COPD), and efforts to increase energy intake are often unsuccessful. The objectives of this study were to determine if there were any taste threshold differences between normal-weight and underweight men with COPD, and to determine if there was any association between absolute and recognition taste thresholds and biochemical data associated with COPD. DESIGN: Cross-sectional comparative. SUBJECTS/SETTING: Potential subjects were identified by their physicians. Forty-six men were willing and eligible to participate. Subjects were given sets of triangle taste tests for 4 tastants: sweet, salty, bitter, and sour. Additional information collected included health history data and biochemical data. Subjects were classified as underweight or normal weight for comparison. STATISTICAL ANALYSES PERFORMED: Independent t tests and one-way analysis of variance were used to determine differences between persons in the underweight (n = 17) and normal-weight (n = 29) groups, and the influence of confounding variables. Bivariate correlations were used to determine associations between tastant thresholds and biochemical indexes for the entire group (N = 46). Stepwise regression analysis was used to determine significant variables in prediction of thresholds of the 4 tastants for the entire group (N = 46). RESULTS: Underweight subjects had a significantly higher bitter taste threshold than normal-weight subjects (5.76 vs 5.10, P = .016). A significant negative correlation was found between absolute bitter and bicarbonate (r = -.39, P = .01) and PCO2 (r = -.34, P = .02). A significant regression equation for absolute bitter taste threshold was determined (P = .011) on the basis of bicarbonate values; and upon body mass index for bitter taste recognition threshold (P = .031). APPLICATIONS: Recognition that patients with COPD may have alterations in taste that are associated with weight status and/or biochemical status can guide dietitians in their recommendations for meal plans targeting individual weight goals.

J Nutr. 1999 Nov;129(11):2043-7.

Dietary potassium bicarbonate and potassium citrate have a greater inhibitory effect than does potassium chloride on magnesium absorption in wethers.
Schonewille JT, Beynen AC, Van't Klooster AT, Wouterse H, Ram L.
Department of Nutrition, Faculty of Veterinary Medicine, Utrecht University, 3508 TD Utrecht, The Netherlands.

We addressed the question whether the type of anion in potassium salts affects magnesium absorption and the transmural potential difference by using wethers (n = 8) fed a control diet and diets supplemented with equimolar amounts of KHCO(3), KCl or K-citrate according to a Latin-square design. The control diet contained 10.9 g K/kg dry matter and the high K diets contained 41.3 g K/kg dry matter. Compared with the control diet, KHCO(3) and K-citrate significantly reduced apparent Mg absorption by 9.5 and 6.5%, respectively. Supplemental KCl tended to reduce (P = 0.070) group mean magnesium absorption by 5.5%. Consumption of supplemental KHCO(3) and K-citrate produced a significant increase in the transmural potential difference (serosal side = positive) by 17.1 and 20.7 mV, respectively, whereas the addition of KCl to the diet did not. The individual values for the four diets tended to show a negative correlation (r = -0.336, n = 32, P = 0.060) between the transmural potential difference and apparent magnesium absorption. We conclude that different potassium salts have different effects on magnesium absorption in ruminants as caused by different effects on the transmural potential difference.

Artif Organs. 1998 Jul;22(7):614-7.
Heparin-induced hyperkalemia in chronic hemodialysis patients: comparison of low molecular weight and unfractionated heparin.
Hottelart C, Achard JM, Moriniere P, Zoghbi F, Dieval J, Fournier A.
Service de Nephrologie, Medecine Interne, CHU Amiens, France.

Aldosterone suppression and subsequent hyperkalemia are well described reversible side effects of prolonged treatment with heparin. This study was designed to examine whether the discontinuous use of heparin three times a week to prevent thrombosis formation during hemodialysis sessions could also induce hypoaldosteronism and might contribute to increased predialysis kalemia in hemodialysis patients. Two different heparinization regimens were prospectively compared in a crossover study of 11 chronic hemodialysis patients. During 2 consecutive weeks, the patients were dialyzed each week with either their usual doses of unfractionated heparin (UH) (6,160 IU +/- 1,350 IU) or low molecular weight heparin (LMWH) (15 anti-Xa activity [aXa] U/kg + 5 aXa U/kg/h). In all but 2 patients, the predialysis level of plasma K+ was higher with UH than with LMWH, and the mean value was higher (5.66+/-0.83 versus 5.15+/-0.68 mM, p = 0.01) while no differences in the predialysis plasma concentrations of creatinine, phosphate, urea, and bicarbonate were observed, excluding the potential role of differences in diet and dialysis efficacy in explaining the higher plasma K+ concentration with UH. The mean plasma aldosterone to plasma renin activity (pRA) ratio was higher with LMWH than with UH (149.54+/-123.1 versus 111.91+/-86.22 pg/ng/ h, p < 0.05). Individual plasma aldosterone values were found to be correlated to pRAs both during the UH period and the LMWH period, and the slope of the positive linear relation between plasma aldosterone and pRA was lower during the UH treatment period (63 versus 105 pg/ng/h). Finally, a negative linear correlation was found between the differences in individual predialysis plasma K+ observed during the 2 protocols and the differences in the corresponding plasma aldosterone levels, suggesting a link between the higher kalemia and the lower aldosterone responsiveness to angiotensin with unfractionated heparin. Although it cannot be concluded whether or not LMWH inhibits aldosterone synthesis, should LMWH decrease aldosterone production, this side effect is 33% less marked than that of UH so that the predialysis plasma K+ levels are 10% lower. This property makes LMWH use preferable to that of UH in patients with elevated predialysis kalemia.

Arch Dis Child. 1977 Apr;52(4):255-67.
Congenital chloride diarrhoea. Clinical analysis of 21 Finnish patients.
Holmberg C, Perheentupa J, Launiala K, Hallman N.

Clinical findings in 21 Finnish children with congenital chloride diarrhoea are reported. Inheritance of this disease by the autosomal recessive mode is established. All children were born 1-8 weeks prematurely. Hydramnios was present in every case and no meconium was observed; intrauterine onset of diarrhoea is thus apparent. In most cases the diarrhoea or passing of large volumes of "urine" was noted on the first day of life and the abdomen was usually large and distended. The neonatla weight loss was abnormally large, and was associated with hypochloraemia and hyponatraemia. Some infants survived the neonatal period without adequate therapy. They presented later with failure to thrive and usually had hypochloraemia, hypokalaemia, and metabolic alkalosis associated with hyperaldosteronism. However, these features may be absent and the diagnosis is based on a history of hydramnios and diarrhoea, and a faecal Cl- concentration which always exceeds 90 mmol/l when fluid and electrolyte deficits have been corrected. Lower faecal Cl- concentrations were seen only in chronic hypochloraemia, which is also associated with achloriduria. Adequate treatment consists of full continuous replacement of the faecal losses of water, NaCl, and KCl. This should be given intravenously in the early neonatal period; later a solution can be taken orally with meals. The dose has to be adjusted to maintain normal serum electrolyte concentrations, normal blood pH, and some chloriduria. This therapy prevents the renal lesions and the retarded growth and psychomotor development which were seen in the children who were diagnosed late and in those who received inadequate replacement therapy. The watery diarrhoea persists and increases slightly with age, though patients learn to live with their disease and to make an adequate social adjustment.

Acta Med Scand Suppl. 1986;707:33-6.
Intracellular electrolytes in cardiac failure.
Wester PO, Dyckner T.

In congestive heart failure (CHF) there are several compensatory mechanisms operating which may influence electrolyte metabolism. The activation of the renin-angiotensin-aldosterone system causes retention of sodium (Na) and losses of potassium (K) and magnesium (Mg). The secondary hyperaldosteronism may give rise to high intracellular Na and low intracellular K through a direct permeability effect on the cell membrane. The Mg deficiency may lead to a further increase of intracellular Na and decrease of intracellular K since Mg is a necessary ion for the function of the Na-K pump. In 297 patients with diuretic treated CHF we found that 42% had hypokalemia, 37% hypomagnesemia and 12% hyponatremia. We also found that 57% had excess muscle Na, 52% had depletion of muscle K and 43% had low muscle Mg. We have also shown that the low muscle K cannot be corrected by K supplementation when there is a concomitant Mg deficiency and that Mg infusions may change the disturbed relation between extra-and intracellular electrolytes towards normal.

Eur J Clin Nutr. 2004 Feb;58(2):270-6.

Influence of a mineral water rich in calcium, magnesium and bicarbonate on urine composition and the risk of calcium oxalate crystallization.
Siener R, Jahnen A, Hesse A.
Division of Experimental Urology, Department of Urology, University of Bonn, Bonn, Germany.

OBJECTIVE: To evaluate the effect of a mineral water rich in magnesium (337 mg/l), calcium (232 mg/l) and bicarbonate (3388 mg/l) on urine composition and the risk of calcium oxalate crystallization. DESIGN: A total of 12 healthy male volunteers participated in the study. During the baseline phase, subjects collected two 24-h urine samples while on their usual diet. Throughout the control and test phases, lasting 5 days each, the subjects received a standardized diet calculated according to the recommendations. During the control phase, subjects consumed 1.4 l/day of a neutral fruit tea, which was replaced by an equal volume of a mineral water during the test phase. On the follow-up phase, subjects continued to drink 1.4 l/day of the mineral water on their usual diet and collected 24-h urine samples weekly. RESULTS: During the intake of mineral water, urinary pH, magnesium and citrate excretion increased significantly on both standardized and normal dietary conditions. The mineral water led to a significant increase in urinary calcium excretion only on the standardized diet, and to a significantly higher urinary volume and decreased supersaturation with calcium oxalate only on the usual diet. CONCLUSIONS: The magnesium and bicarbonate content of the mineral water resulted in favorable changes in urinary pH, magnesium and citrate excretion, inhibitors of calcium oxalate stone formation, counterbalancing increased calcium excretion. Since urinary oxalate excretion did not diminish, further studies are necessary to evaluate whether the ingestion of calcium-rich mineral water with, rather than between, meals may complex oxalate in the gut thus limiting intestinal absorption and urinary excretion of calcium and oxalate.

J Med Assoc Thai. 2002 Nov;85 Suppl 4:S1143-9.

The optimal dose of potassium citrate in the treatment of children with distal renal tubular acidosis.

Tapaneya-Olarn W, Khositseth S, Tapaneya-Olarn C, Teerakarnjana N, Chaichanajarernkul U, Stitchantrakul W, Petchthong T.

Department of Pediatrics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand.

BACKGROUND: Distal renal tubular acidosis (RTA) is a common cause of intractable calcium nephrolithiasis. In adults, the use of potassium citrate (PC) in distal RTA effectively decreases metabolic acidosis and the risk of calcium oxalate stone but it cannot decrease the risk of calcium phosphate stone. However, there is no report for the optimal dose of PC and the risk of calcium stone in distal RTA in children. OBJECTIVE: To evaluate the optimal dose of PC that minimizes the risk of calcium nephrolithiasis in children with distal RTA. METHOD: Prospective study PATIENTS: Children who have distal RTA and were followed-up for 4 months. Patients were studied in a control phase, 1 month of PC 2 mEq/kg/day, 2 months of PC 3 mEq/kg/day and 1 month of PC 4 mEq/kg/day. The urine specimens of 41 normal children were measured for the reference value of the parameters determining the risk of calcium stone. RESULTS: Eight children (mean age of 10 +/- 3.7 years, female : male = 6: 2) with distal RTA were studied during the control phase and after receiving PC 2 mEq/kg/day for I month. Treatment with PC 2 mEq/kg/day was not able to normalize serum bicarbonate and caused no significant change in the urine citrate/creatinine ratio, and activity production of calcium phosphate stone but it caused a significant decrease in the urine calcium/citrate ratio. Although PC 3 mEq/kg/day for I month normalized plasma bicarbonate, only this dose given for 2 months caused a significant increase in the urine citrate/creatinine ratio and urine calcium/ citrate ratio to values that were not different from normal children, while the activity production of calcium phosphate stone did not decrease to normal level. The effect of PC 4 mEq/kg/day was similar to that of 3 mEq/kg/day. CONCLUSION: Potassium citrate 3 mEq/kg/day for 2 months effectively normalized serum bicarbonate and decreased the risk of calcium oxalate stone but this treatment was theoretically unable to reduce the risk of calcium phosphate stone in children with distal RTA.

J Ren Nutr. 1998 Jul;8(3):127-31.
Potassium and sodium intake and excretion in calcium stone forming patients.
Martini LA, Cuppari L, Cunha MA, Schor N, Heilberg IP.
Master in Science, Universidade Federal de Sao Paulo-EPM, Sao Paulo, Brazil.

OBJECTIVE: To determine mean potassium (K) intake and its correlation with urinary calcium (uCa) and citrate excretion, as well as uCa, sodium (Na), and K levels of calcium stone forming patients. We determined the K-rich foods most commonly consumed by these patients. DESIGN: Case-control. SETTING: University-affiliated outpatient renal Lithiasis Unit. PATIENTS AND CONTROLS: One hundred hypercalciuric calcium stone forming patients (CSF, 54 men/46 women), 37 with associated hypocitraturia, were sequentially enrolled in the study that was performed before the initiation of any care for their renal stones. The control group consisted of 100 age-matched healthy subjects (HS, 47 men/53 women) who were laboratory employees with no history of renal stones. INTERVENTION: The analyses consisted of a 3-day dietary record to determine the mean K and calcium (Ca) intakes, and a 24-hour urine sample with measurements of K, Ca, Na, and citrate. MAIN OUTCOME MEASURE: K and Na intake determined by dietary record. RESULTS: uCa and Na levels and the Na/K ratio were significantly higher for CSF versus HS (238 +/- 118 v 148 +/- 74 mg/24 hours, 238 +/- 100 v 181 +/- 68 mEq/24 hours, 6.6 +/- 3.5 v 5.1 +/- 2.3, respectively, P < .05). The mean citrate excretion was lower in CSF than in HS patients (410 +/- 265 v 530 +/- 240 mg/24 hours). Mean uCa did not differ between groups. CSF patients showed a higher sodium chloride intake compared with HS (14 +/- 4 vs 8 +/- 3 g/day). The mean Ca intake of CSF and HS were 559 +/- 327 and 457 +/- 363 mg/day, respectively. The mean K intake of CSF and HS were 58 +/- 17 and 51 +/- 27 mEq/day. A positive correlation was observed between uCa and urinary sodium (r = .40 and r = .65, P < .05), urinary potassium and urinary citrate (r = .25 and r = .53, P < .05), uCa and Na/K (r = .33 and r = .56, P < .05) respectively for CSF and HS. The following were the K-rich foods consumed at least once a day by these groups: beans (by 70% of CSF and 75% of HS), tomatoes (by 42% of CSF and 50% of HS), oranges (by 30% of CSF and 55% of HS), and bananas (by 42% of CSF and 23% of HS). CONCLUSION: Despite the consumption of K-rich foods at least once a day, the mean K intake by CSF patients was 58 mEq/day. This intake can still be considered to be low, although it meets recommended daily dietary allowance requirements. Therefore, we describe herein a population of CSF with high-Na intake and normal- to low-K intake, which may contribute to stone formation.

J Am Coll Nutr. 1998 Apr;17(2):148-54.

Calciuric effects of short-term dietary loading of protein, sodium chloride and potassium citrate in prepubescent girls.
Duff TL, Whiting SJ.
College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Canada.

OBJECTIVE: Studies using adult human subjects indicate that dietary protein and sodium chloride have negative effects on the retention of calcium by increasing urinary calcium excretion, while alkaline potassium improves calcium retention along with decreasing urinary calcium losses. This study investigated the effect of these dietary factors on acute urinary calcium excretion in 14 prepubescent girls age 6.7 to 10.0 years. METHODS: Subjects provided a fasting urine sample then consumed a meal containing one of five treatments: moderate protein (MP) providing 11.8 g protein, moderate protein plus 26 mmol sodium chloride (MP+Na), high protein (HP) providing 28.8 g protein, high protein plus 26 mmol sodium chloride (HP+Na), or high protein plus 32 mmol potassium as tripotassium citrate (HP+K). Urine was collected at 1.5 and 3.0 hours after the meal. Supplemental protein was given as 80:20 casein:lactalbumin. Test meals were isocaloric, and unless intentionally altered, components of interest except phosphate were equal between treatments. Each subject completed all five treatments. RESULTS: Urinary calcium excretion rose after the meal, peaking at 1.5 hours. There were no significant differences in calcium excretion between treatments at any time point. The high protein treatments did not result in a significant increase in either net acid or sulfate excretion at 1.5 hours compared to moderate protein. Dietary sodium chloride had no effect on urinary sodium or calcium excretion over the 3 hours. After the potassium treatment, sodium excretion increased (p< or =0.002) and net acid excretion decreased (p<0.001) compared to other treatments at 1.5 hours. CONCLUSIONS: In children, a simultaneous increase in protein and phosphorus due to increased milk protein intake did not increase acute urinary calcium excretion. An effect of dietary sodium chloride on acute urinary calcium excretion was not observed. Both these findings were similar to those of adult studies previously conducted in the same laboratory using similar format and treatments. Potassium citrate was not hypocalciuric in children, a response differing from that for adults, who have shown a decrease in acute urinary calcium excretion in response to alkaline potassium treatment. Further characterization of calciuric responses to dietary factors is required for children, who may differ from adults in many respects.

Magnesium. 1984;3(4-6):324-38.
Influence of intravenous Mg++ solutions on renal excretion of potassium, sodium, calcium, chloride, intraleukocytic potassium and peripheral vascular resistance: a metabolic and hemodynamic study in normal volunteers.
Glanzer K, Schlebusch H, Sorger M, Pannenbecker D, Kruck F.

In an open randomized crossover trial 8 healthy male volunteers received an intravenous infusion of potassium chloride, potassium/magnesium chloride, potassium-(D,L)-aspartate, and potassium/magnesium-(D,L)-aspartate. Equimolar amounts of potassium (27.75 mmol) and magnesium (13.9 mmol) were given in a 500-ml volume during 24 h. During two 9-day periods subjects were maintained on a constant diet with a daily intake of 80 mmol potassium and 60 mmol magnesium. Infusions were administered on day 5 and 7 of each period. Serum and urine electrolyte concentrations as well as intraleukocyte potassium were measured before, during, and after the tests; cardiac output and systemic vascular resistance were determined by impedance cardiography. Potassium and magnesium containing solutions did not influence renal elimination of potassium, and also the circadian rhythm of potassium excretion did not show any change. The elimination of sodium, calcium, potassium, and chloride rose significantly over the corresponding control values during magnesium infusions, but not when potassium salts were given. The increase of calcium excretion after Mg++ is most probably due to suppression of parathyroid hormone. Intraleukocyte potassium was not affected significantly by the various infusions, indicating that intracellular compartments are completely filled. There was no evidence that the anion (D,L-aspartate or chloride) had a significant effect on all measured variables. Mean arterial blood pressure and peripheral vascular resistance were not altered significantly during the infusions.

Am J Kidney Dis. 1998 Jan;31(1):19-27.
On the mechanism of the effects of potassium restriction on blood pressure and renal sodium retention.
Gallen IW, Rosa RM, Esparaz DY, Young JB, Robertson GL, Batlle D, Epstein FH, Landsberg L.
Department of Medicine, Northwestern University Medical School, Chicago, IL, USA.

Dietary potassium restriction increases sodium and chloride retention, whereas potassium administration promotes both diuresis and natriuresis. In epidemiologic and clinical studies, potassium intake is inversely related to blood pressure and is lower in blacks than in whites. The present studies examined the mechanism by which potassium restriction fosters sodium conservation and the impact of race on this response. Twenty-one healthy black and white men and women ingested an isocaloric, potassium-restricted diet (20 mmol/d) containing 180 mmol/d of sodium with and without a potassium supplement (80 mmol/d) for 9 days on two occasions. Additionally, eight of these subjects ingested the same diets for 3 days followed by a water load to determine free water clearance before and during the early phase of dietary potassium restriction. During potassium restriction, mean arterial pressure (MAP) derived from 24-hour blood pressure measurements was higher (85.7 +/- 1.6 mm Hg v 82.0 +/- 1.3 mm Hg; P < 0.001), cumulative sodium excretion lower (984 +/- 59 mmol/d v 1,256 +/- 58 mmol/d; P < 0.001), and weight greater (71.1 +/- 2.1 kg v 69.3 +/- 2.2 kg; P < 0.001). Blacks displayed no greater increase in MAP, although they excreted less sodium overall and less potassium on the potassium-supplemented diet. After a water load, minimum urine osmolality (Uosm) was lower (53.0 +/- 3.0 mOsm/L v 65.6 +/- 3.5 mOsm/L; P = 0.01) and free water clearance greater (4.44 +/- 0.59 mL/min v3.72 +/- 0.58 mL/min; P = 0.009) during potassium restriction. In conclusion, in healthy, normotensive subjects, potassium restriction was associated with an increase in blood pressure and volume expansion effected by increased renal sodium and chloride retention. Potassium restriction was also associated with increased free water clearance and enhanced diluting capacity consistent with augmentation of Na+, K+:2Cl- cotransporter activity in the thick ascending limb of Henle. This mechanism may play an important role in the renal adaptation required for potassium conservation, but at the expense of sodium chloride retention and an elevation in blood pressure. 

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