Association between hypomagnesemia and severity of primary hyperparathyroidism: a retrospective study

BACKGROUND

The occurrence of hypomagnesemia in patients with primary hyperparathyroidism (PHPT) has been noted previously; however, the association of hypomagnesemia and severity of primary hyperparathyroidism remains unknown. The present study aimed to evaluate the association of hypomagnesemia with biochemical and clinical manifestations in patients with PHPT.

METHODS

This was a retrospective study conducted at a tertiary hospital. We obtained data from 307 patients with PHPT from January 2010 through August 2020. Data on demographics, history, laboratory findings, bone densitometry findings, and clinical presentation and complications were collected and were compared in normal magnesium group vs hypomagnesemia group.

RESULTS

Among the 307 patients with PHPT included in our study, 77 patients (33/102 [32.4%] males and 44/205 [21.5%] females) had hypomagnesemia. Mean hemoglobin levels in the hypomagnesemia group were significantly lower than those in the normal magnesium group in both males and females. In contrast, patients with hypomagnesemia had a higher mean serum calcium and parathyroid hormone than individuals with normal magnesium. The typical symptoms of PHPT, such as nephrolithiasis, bone pain/fractures, polyuria, or polydipsia, were more common in the hypomagnesemia group. In addition, patients with hypomagnesemia had a higher prevalence of osteoporosis, anemia, and hypercalcemic crisis. Even after adjusting for potential confounders, including age, sex, body mass index, estimated glomerular filtration rate, and parathyroid hormone levels, these associations remained essentially unchanged.

CONCLUSION

Biochemical and clinical evidence indicates that patients with PHPT with hypomagnesemia have more severe hyperparathyroidism than those without hypomagnesemia. In addition, PHPT patients with hypomagnesemia had a higher prevalence of osteoporosis, anemia, and hypercalcemic crisis.

Renal effects of uric acid: hyperuricemia and hypouricemia

The prevalence of chronic kidney disease (CKD) is increasing worldwide. Although hyperuricemia has been associated with CKD in many studies, it remains controversial whether this is the cause or the result of decreased renal function. Recent observational studies of healthy populations and patients with CKD have reported that uric acid (UA) has an independent role in the development or progression of CKD. Experimental studies have shown several potential mechanisms by which hyperuricemia may cause or promote CKD. However, other reports have indicated an association between hypouricemia and CKD. This opposing effect is hypothesized to occur because UA is a major antioxidant in human plasma and is associated with oxidative stress. In this article, we discuss the potential association between UA imbalance and CKD and how they can be treated.

U-Shaped Association of Serum Uric Acid With All-Cause and Cause-Specific Mortality in US Adults: A Cohort Study

BACKGROUND

In addition to the controversy regarding the association of hyperuricemia with mortality, uncertainty also remains regarding the association between low serum uric acid (SUA) and mortality. We aimed to assess the relationship between SUA and all-cause and cause-specific mortality.

METHODS

This cohort study included 9118 US adults from the National Health and Nutrition Examination Survey (1999-2002). Multivariable Cox proportional hazards models were used to evaluate the relationship between SUA and mortality. Our analysis included the use of a generalized additive model and smooth curve fitting (penalized spline method), and 2-piecewise Cox proportional hazards models, to address the nonlinearity between SUA and mortality.

RESULTS

During a median follow-up of 5.83 years, 448 all-cause deaths occurred, with 100 cardiovascular disease (CVD) deaths, 118 cancer deaths, and 37 respiratory disease deaths. Compared with the reference group, there was an increased risk of all-cause, CVD, cancer, and respiratory disease mortality for participants in the first and third tertiles of SUA. We further found a nonlinear and U-shaped association between SUA and mortality. The inflection point for the curve was found at a SUA level of 5.7 mg/dL. The hazard ratios (95% confidence intervals) for all-cause mortality were 0.80 (0.65-0.97) and 1.24 (1.10-1.40) to the left and right of the inflection point, respectively. This U-shaped association was observed in both sexes; the inflection point for SUA was 6 mg/dL in males and 4 mg/dL in females.

CONCLUSION

Both low and high SUA levels were associated with increased all-cause and cause-specific mortality, supporting a U-shaped association between SUA and mortality.

Short-Term Effect of High-Dose Pantoprazol on Serum and Urinary Magnesium Levels

BACKGROUND

Proton pump inhibitor (PPI) induced hypomagnesemia is a completely unexplained issue and cases are still being reported. Long-term use is the main factor, but there are a few articles stating that it may also emerge with short-term use. We aimed to evaluate the changes of serum and urine magnesium levels during shortterm high dose pantoprazol treatment.

METHODS

The serum and 24-hour urine magnesium levels of 58 patients were evaluated during the course of 2 days. Of 58 patients, 25 were allowed oral intake on the 3rd day of hospitalization and thus, 24-hour urine for 3 days was collected from 33 patients.

RESULTS

There were no significant differences in the mean levels of serum magnesium and the median levels of urine magnesium. When the magnesium levels were evaluated by age over and under 60 years, the baseline serum magnesium level was significantly higher than the 1st level in patients aged ≥ 60 years (p = 0.029). The 3rd day serum magnesium level was significantly higher than the baseline and 1st day levels in those aged < 60 years (p = 0.049).

CONCLUSIONS

We showed that plasma levels and urinary excretion of magnesium did not change significantly during high-dose pantoprazol treatment. It can be hypothesized that magnesium levels are not affected by PPIs in short-term usage. Age and other contributing factors may have more impact on PPI induced hypomagnesemia. Patients aged over 60 years might be handled carefully under proton pump inhibitors treatment.

Hypomagnesemia and Survival in Patients with Ovarian Cancer Who Received Chemotherapy with Carboplatin

BACKGROUND

Hypomagnesemia is a known side effect of several antineoplastic agents, but its impact on outcomes of patients with cancer is not well understood. We examined whether magnesium abnormalities affect survival in patients with ovarian cancer who receive chemotherapy containing carboplatin.

MATERIALS AND METHODS

We included patients with advanced ovarian cancer who had undergone surgery and chemotherapy between January 1, 2004, and December 31, 2014, at our institution. Inclusion criteria were age 18 years or older, pathology of high-grade serous carcinoma, first treatment (surgery or chemotherapy) within 60 days of diagnosis, and chemotherapy containing carboplatin. The final cohort consisted of 229 patients. Vital signs and laboratory tests were recorded at baseline and during the treatment course. The associations between magnesium abnormalities (and other clinical characteristics) and survival were analyzed.

RESULTS

The median patient age was 64 years. Higher baseline heart rate (beats per minute; hazard ratio [HR] = 1.02, p = .002) and greater frequency of hypomagnesemia during the treatment course (HR = 1.05, p = .002) were significantly associated with shorter survival independent of completeness of tumor reduction (HR = 1.60, p = .02), and International Federation of Gynecology and Obstetrics stage (HR = 1.63, p = .01).

CONCLUSION

Baseline heart rate and the frequency of hypomagnesemia episodes during treatment are prognostic of survival for patients with advanced ovarian cancer receiving carboplatin-containing chemotherapy and tumor reductive surgery. Future research is needed for strategies to detect and prevent hypomagnesemia in this patient population.

IMPLICATIONS FOR PRACTICE

Despite standard laboratory tests and intravenous magnesium replacement prior to each cycle of chemotherapy, hypomagnesemia remains a common side effect of platinum-based chemotherapy. This study revealed that frequent occurrence of hypomagnesemia during the course of treatment including carboplatin-containing chemotherapy and tumor reductive surgery was strongly predictive of shorter survival in patients with advanced ovarian cancer. Strategies to effectively mitigate hypomagnesemia, such as more frequent detection, dietary recommendations, and timely replacement, should be considered in the overall cancer treatment plan for these patients.

Genetic causes of hypomagnesemia, a clinical overview

Magnesium is essential to the proper functioning of numerous cellular processes. Magnesium ion (Mg2+) deficits, as reflected in hypomagnesemia, can cause neuromuscular irritability, seizures and cardiac arrhythmias. With normal Mg2+ intake, homeostasis is maintained primarily through the regulated reabsorption of Mg2+ by the thick ascending limb of Henle's loop and distal convoluted tubule of the kidney. Inadequate reabsorption results in renal Mg2+ wasting, as evidenced by an inappropriately high fractional Mg2+ excretion. Familial renal Mg2+ wasting is suggestive of a genetic cause, and subsequent studies in these hypomagnesemic families have revealed over a dozen genes directly or indirectly involved in Mg2+ transport. Those can be classified into four groups: hypercalciuric hypomagnesemias (encompassing mutations in CLDN16, CLDN19, CASR, CLCNKB), Gitelman-like hypomagnesemias (CLCNKB, SLC12A3, BSND, KCNJ10, FYXD2, HNF1B, PCBD1), mitochondrial hypomagnesemias (SARS2, MT-TI, Kearns-Sayre syndrome) and other hypomagnesemias (TRPM6, CNMM2, EGF, EGFR, KCNA1, FAM111A). Although identification of these genes has not yet changed treatment, which remains Mg2+ supplementation, it has contributed enormously to our understanding of Mg2+ transport and renal function. In this review, we discuss general mechanisms and symptoms of genetic causes of hypomagnesemia as well as the specific molecular mechanisms and clinical phenotypes associated with each syndrome.

Hypomagnesemia Is Associated with Increased Mortality among Peritoneal Dialysis Patients

Objective

Hypomagnesemia has been associated with an increase in mortality among the general population as well as patients with chronic kidney disease or those on hemodialysis. However, this association has not been thoroughly studied in patients undergoing peritoneal dialysis. The aim of this study was to evaluate the association between serum magnesium concentrations and all-cause and cardiovascular mortalities in peritoneal dialysis patients.

Methods

This single-center retrospective study included 253 incident peritoneal dialysis patients enrolled between July 1, 2005 and December 31, 2014 and followed to June 30, 2015. Patient’s demographic characteristics as well as clinical and laboratory measurements were collected.

Results

Of 253 patients evaluated, 36 patients (14.2%) suffered from hypomagnesemia. During a median follow-up of 29 months (range: 4–120 months), 60 patients (23.7%) died, and 35 (58.3%) of these deaths were attributed to cardiovascular causes. Low serum magnesium was positively associated with peritoneal dialysis duration (r = 0.303, p < 0.001) as well as serum concentrations of albumin (r = 0.220, p < 0.001), triglycerides (r = 0.160, p = 0.011), potassium (r = 0.156, p = 0.013), calcium(r = 0.299, p < 0.001)and phosphate (r = 0.191, p = 0.002). Patients in the hypomagnesemia group had a lower survival rate than those in the normal magnesium groups (p < 0.001). In a multivariate Cox proportional hazards regression analysis, serum magnesium was an independent negative predictor of all-cause mortality (hazard ratio [HR] = 0.075, p = 0.011) and cardiovascular mortality (HR = 0.003, p < 0.001), especially in female patients. However, in univariate and multivariate Cox analysis, △Mg(difference between 1-year magnesium and baseline magnesium) was not an independent predictor of all-cause mortality and cardiovascular mortality.

Conclusion

Hypomagnesemia was common among peritoneal dialysis patients and was independently associated with all-cause mortality and cardiovascular mortality.

Hypomagnesemia due to two novel TRPM6 mutations

BACKGROUND

Although most hypocalcemia with hypomagenesemia in the neonatal period is due to transient neonatal hypoparathyroidism, magnesium channel defects should also be considered.

CASE

We report a case of persistent hypomagnesemia in an 8-day-old Hispanic male who presented with generalized seizures. He was initially found to have hypomagnesemia, hypocalcemia, hyperphosphatemia and normal parathyroid hormone. Serum calcium normalized with administration of calcitriol and calcium carbonate. Serum magnesium improved with oral magnesium sulfate. However, 1 week after magnesium was discontinued, serum magnesium declined to 0.5 mg/dL. Magnesium supplementation was immediately restarted, and periodic seizure activity resolved after serum magnesium concentration was maintained above 0.9 mg/dL. The child was eventually weaned off oral calcium and calcitriol with persistent normocalemia. However, supraphysiologic oral magnesium doses were necessary to prevent seizures and maintain serum magnesium at the low limit of normal.

METHODS AND RESULTS

As his clinical presentation suggested primary renal magnesium wastage, TRPM6 gene mutations were suspected; subsequent genetic testing revealed the child to be compound heterozygous for TRPM6 mutations.

CONCLUSION

Two novel TRPM6 mutations are described with a new geographic and ethnic origin. This case highlights the importance of recognizing disorders of magnesium imbalance and describing new genetic mutations.

Acute kidney injury in hereditary renal hypouricaemia --a case report and review of literature

A young male patient was admitted to our hospital with history of dysuria, recurrent vomiting, severe muscle pain and weakness which was induced by a session of rigorous exercise for the first time in the local gymnasium. He was subsequently diagnosed with exercise-induced acute kidney injury and rhabdomyolysis and managed accordingly. Later on during follow-up he was found to have extreme hypouricaemia (serum uric acid 0.2 mg/dl) and was subsequently diagnosed with renal hypouricaemia. Biochemical investigations on other family members of the patient revealed hereditary renal hypouricaemia in the family.

SLC22A12 W258X frequency according to serum uric acid level among Japanese health checkup examinees

Although the SLC22A12 (uric acid transporter 1) 258X allele is known to cause hypouricemia, the genotype frequency according to the serum uric acid (SUA) level has not been reported. This study investigated the SLC22A12 258WX frequency according to SUA levels among Japanese health-checkup examinees. In addition, the changes were reported in SUA levels during five years for individuals with 258WX. Subjects were 746 Japanese aged 39-86 years in 2003. Their SUA records were linked during the five years from 2003 to 2007. SLC22A12 W258X was genotyped using a polymerase chain reaction with confronting two-pair primers. The 258X allele comprised 1.9% (95% CI, 1.3-2.8%) of all the subjects. Among those with SUA <3.0 mg/dL, 258WX was more common in males (66.7%, 95% CI, 22.2-95.7%) than in females (39.3%, 95% CI, 21.5-59.4%). Among subjects with a SUA of 3.0-4.9 mg/dL, those with 258WX totaled 10.7% (95% CI, 4.0-21.9%) and 2.6% (95% CI, 1.1-5.0%), respectively. There were no subjects with 258WX among those with a SUA of 5.0 mg/dL or more. During the five years from 2003 to 2007, the changes in SUA among 23 individuals with 258WX were found to be similar to those among 258WW subjects (n=536). This study indicated that SLC22A12 258WX was more common among those with a lower serum uric acid concentration. The observed SUA level changes in individuals with 258WX suggested that lifestyle factors could influence the levels of those with 258WX.

Pseudoaldosteronism with increased serum cortisol associated with pneumonia, hypouricemia, hypocalcemia, and hypophosphatemia

We describe here the interesting case of a 73-year-old hypertensive man with pseudoaldosteronism. He had been taking glycyrrhizin at a dose of 75 mg/day for 12 years because of mild liver damage, but had never experienced any previous symptoms associated with hypokalemia. He was referred to our hospital because of hypokalemic tetraparesis and rhabdomyolysis. At that time, we noted mineralocorticoid excess characterized by hypokalemia due to urinary K loss, exacerbation of hypertension due to increased tubular Na reabsorption, metabolic alkalosis, and suppression of both plasma renin activity and plasma aldosterone concentration. His urinary free cortisol excretion rate and the urinary ratio of free cortisol to free cortisone were markedly elevated. Thus we diagnosed pseudoaldosteronism that was related to the long-term use of glycyrrhizin. When he developed pseudoaldosteronism, he also contracted pneumonia, and exhibited elevated levels of serum cortisol and creatinine clearance (CCr) as well as hypouricemia, hypocalcemia, and hypophosphatemia. All normalized after the recovery from pneumonia and the administration of spironolactone. The extracellular volume expansion associated with increased tubular Na reabsorption by the aldosterone-sensitive distal nephron and the resulting increase in CCr caused an inhibition of proximal tubular reabsorption of uric acid, Ca, and inorganic phosphate, leading to their renal loss and therefore hypouricemia, hypocalcemia, and hypophosphatemia, respectively. In this patient, the increased circulating cortisol associated with the stress of inflammation caused by pneumonia triggered the development of pseudoaldosteronism.

Novel OCRL1 mutations in patients with the phenotype of Dent disease

BACKGROUND

Dent disease is an X-linked tubulopathy frequently caused by mutations affecting the voltage-gated chloride channel and chloride/proton antiporter ClC-5. A recent study showed that defects in OCRL1, encoding a phosphatidylinositol 4,5-bisphosphate 5-phosphatase (Ocrl) and usually found mutated in patients with Lowe syndrome, also can provoke a Dent-like phenotype (Dent 2 disease).

METHODS

We investigated 20 CLCN5-negative males from 17 families with a phenotype resembling Dent disease for defects in OCRL1.

RESULTS

In our complete series of 35 families with a phenotype of Dent disease, a mutation in the OCRL1 gene was detected in 6 kindreds. All were novel frameshift (Q70RfsX88 and T121NfsX122, detected twice) or missense mutations (I257T and R476W). None of our patients had cognitive or behavioral impairment or cataracts, 2 classic hallmarks of Lowe syndrome. All patients had mild increases in lactate dehydrogenase and/or creatine kinase levels, which rarely is observed in CLCN5-positive patients, but frequently found in patients with Lowe syndrome. To explain the phenotypic heterogeneity caused by OCRL1 mutations, we performed extensive data-bank mining and extended reverse-transcriptase polymerase chain reaction analysis, which provided no evidence for yet unknown (tissue-specific) alternative OCRL1 transcripts.

CONCLUSION

Mutations in the OCRL1 gene are found in approximately 23% of kindreds with a Dent phenotype. Defective protein sorting/targeting of Ocrl might be the reason for mildly elevated creatine kinase and lactate dehydrogenase serum concentrations in these patients and a clue to suspect Dent disease unrelated to CLCN5 mutations. It remains to be elucidated why the various OCRL1 mutations found in patients with Dent 2 disease do not cause cataracts.

Inherited Renal Tubulopathies Associated With Metabolic Alkalosis: Effects on Blood Pressure

Inherited tubular disorders associated with metabolic alkalosis are caused by several gene mutations encoding different tubular transporters responsible for NaCl renal handling. Body volume and renin-angiotensin-aldosterone system status are determined by NaCl reabsorption in the distal nephron. Two common hallmarks in affected individuals: hypokalemia and normal / high blood pressure, support the differential diagnosis. Bartter's syndrome, characterized by hypokalemia and normal blood pressure, is a heterogenic disease caused by the loss of function of SLC12A1 (type 1), KCNJ1 (type 2), CLCNKB (type 3), or BSND genes (type 4). As a result, patients present with renal salt wasting and hypercalciuria. Gitelman's syndrome is caused by the loss of funcion of the SLC12A3 gene and may resemble Bartter's syndrome, though is associated with the very low urinary calcium. Liddle's syndrome, also with similar phenotype but with hypertension, is produced by the gain of function of the SNCC1B or SNCC1G genes, and must be distinguished from other entities of inherited hypertension such as Apparently Mineralocorticoid Excess, of glucocorticoid remediable hypertension.

Autosomal recessive renal proximal tubulopathy and hypercalciuria: a new syndrome

BACKGROUND

The best described primary inherited proximal tubulopathies include X-linked hypercalciuric nephrolithiasis (XLHN), caused by a mutation in the chloride channel gene CLCN5, and classic Fanconi's syndrome, the genetic basis of which is unknown. The aim of this study is to examine the clinical, biochemical, and genetic characteristics of a highly consanguineous Druze family with autosomal recessive proximal tubulopathy and hypercalciuria (ARPTH), a syndrome not reported previously.

METHODS

Three children (2 girls, 1 boy) of the family referred for evaluation of renal glycosuria and hypercalciuria and 10 of their close relatives were evaluated clinically and biochemically. All study participants underwent genetic analysis to exclude involvement of the CLCN5 gene.

RESULTS

Evaluation of the 3 affected children showed glycosuria, generalized aminoaciduria, hypouricemia, uricosuria, low molecular weight (LMW) proteinuria, and hypercalciuria in all 3 children and phosphaturia in 2 children. They had no metabolic acidosis or renal insufficiency. One affected girl had nephrocalcinosis. Two children had a history of growth retardation and radiological findings of metabolic bone disease. Parathyroid hormone and 1,25-dihydroxyvitamin D [1,25(OH)2Vit D] blood levels in affected children were normal. Unaffected family members examined had no renal tubular defects or LMW proteinuria. Genetic linkage analysis excluded cosegregation of the ARPTH phenotype with the CLCN5 locus.

CONCLUSION

ARPTH is a new syndrome characterized by nonacidotic proximal tubulopathy, hypercalciuria, metabolic bone disease, and growth retardation. It can be distinguished from XLHN by its autosomal recessive mode of inheritance and normal serum levels of calciotropic hormones, as well as the absence of LMW proteinuria in obligate carriers. The gene mutated in ARPTH remains to be identified.

[The Gitelman syndrome--a differential diagnosis of Bartter syndrome]

BACKGROUND

Hypokalemia due to renal potassium wasting in the absence of hypertension, moderate metabolic alkalosis, hyperreninism and hyperaldosteronism suggest the presence of Bartter's syndrome. The underlying cause is an inherited defect of sodium chloride reabsorption in the thick ascending limb of Henle. A differential diagnosis of Bartter's syndrome is Gitelman's syndrome, another hypokalemia-hypomagnesemia syndrome, which is thought to be caused by a transport defect in the distal tube.

PATIENTS AND METHODS

We report 3 patients presenting with signs primarily suggestive of Bartter's syndrome, who turned out to have Gitelman's syndrome after determining the excretion of calcium in the urine.

RESULTS

Two women, 36- and 55-year old, suffered from paresthesias in the hands and feet and from tetanic convulsions. The brother of the 36-year old woman presented in our hospital because of an accidentally discovered hypokalemia without any clinical symptoms. In all patients the outstanding biochemical features were hypokalemia, hypomagnesemia and moderate metabolic alcalosis. The renin and aldosterone values were inappropriately high. The most characteristic finding in the urine, besides the presence of hyperkaliuria was the diminution of calcium excretion, despite normocalcemia.

CONCLUSION

The association between sodium and calcium reabsorption in the loop of Henle predicts hypercalciuria in patients with a defect in salt reabsorption in this segment, as in Bartter's syndrome. In Gitelman's syndrome the laboratory features resemble the findings in Bartter's syndrome, except for the presence of hypocalciuria. Since hypocalciuria follows also the administration of thiazide diuretics, which act in the early part of distal tube, a transport defect in this part of the tube is thought to be responsible for the electrolyte disturbances in Gitelman's syndrome. The measurement of the urinary calcium excretion in patients with an unclear hypokalemia-hypomagnesemia-syndrome allows easily the differentiation between Bartter's and Gitelman's syndrome.

Chronic hypomagnesemia and hypokalemia due to renal wasting in siblings

A 13 year old girl with carpopedal spasm is presented. Investigation values showed hypomagnesemia and hypokalemia. Her younger brother and sister demonstrated the same biochemical abnormalities without any symptoms. Their urinary excretion of magnesium and potassium were inappropriately high compared with their serum levels. Treatment with oral magnesium sulfate failed to correct the abnormalities, but serum levels of magnesium and potassium were just below the lower limits. This familial disease may represent congenital renal wasting of magnesium and potassium.

Correlations of serum concentrations of 1,25-dihydroxyvitamin D, phosphorus, and parathyroid hormone in tumoral calcinosis

The inherited metabolic disorder tumoral calcinosis is characterized by elevated serum phosphorus and 1,25-dihydroxyvitamin D [1,25-(OH)2D] levels and paraarticular calcific tumors. The pathogenesis of this disease is obscure, but an elevated renal phosphate reabsorption threshold and increased production of 1,25-(OH)2D are postulated as defects. We studied nine affected patients and found that both serum phosphorus and renal phosphate reabsorption threshold (TmP/GFR) were positively correlated with serum 1,25-(OH)2D levels. Since tumoral calcinosis is a disorder with abnormal renal phosphate transport, we compared the TmP/GFR and serum 1,25-(OH)2D levels to values obtained in patients with two other diseases with renal phosphate transport defects: oncogenic osteomalacia and X-linked hypophosphatemic rickets. We found a significant correlation between TmP/GFR and 1,25-(OH)2D levels in all three diseases, suggesting that in these diseases 1,25-(OH)2D production is regulated in some manner by phosphate transport. Furthermore, previous work indicated that in tumoral calcinosis broad variation exists in serum phosphorus levels. In our patients a negative correlation was found between the serum PTH concentrations and both serum phosphorus levels and TmP/GFR values, respectively. We postulate that although the basic defect in tumoral calcinosis most likely resides in the proximal renal tubular cell, the variation in serum phosphorus levels and possibly disease expression is modulated in part by PTH.

Lack of effect of aldosterone on intracellular sodium and potassium in mononuclear leucocytes from patients with pseudohypoaldosteronism

In three patients with pseudohypoaldosteronism the effects of aldosterone on intracellular sodium and potassium were studied and compared with normal controls in whom aldosterone prevents the loss of sodium and potassium in vitro. Mononuclear leukocytes were incubated with or without aldosterone (1.4 nM) in RPMI-1640 for 1 h at 37 degrees C. After two washes in isotonic MgCl2 the wet cell pellets were weighted and intracellular sodium and potassium determined by flame photometry, results are expressed as mmol/kg wet cells. In the patients intracellular sodium fell from 18, 23 and 29 mmol/kg to 14, 18 and 11 mmol/kg, respectively, in the absence of aldosterone. With aldosterone added to the incubation medium sodium was not different from values obtained without aldosterone (15, 20 and 13 mmol/kg). Corresponding values for potassium were 89, 48 and 75 mmol/kg before and 68, 32 and 51 mmol/kg after incubation without and 69, 36 and 54 mmol/kg after incubation with aldosterone. Thus, incubation with aldosterone did not show an effect on intracellular sodium and potassium as seen in normals. Baseline values of sodium and potassium before the incubation were within the normal range. From these results it is concluded that in patients with pseudohypoaldosteronism the absent or decreased number of mineralocorticoid receptors in mononuclear leucocytes are accompanied by a lack of response of intracellular sodium and potassium to aldosterone in vitro. However, normal baseline intracellular electrolyte concentrations in these patients may indicate that mineralocorticoids are not involved in the maintenance of normal levels of intracellular sodium and potassium.

[Familial proximal tubular azotemia. Elevated urea plasma levels in normal kidney function]

A family showed a renal disturbance, characterized by an elevated urea plasma concentration while glomerular filtration was found to be normal. A detailed study of renal clearance was performed on two members of this family in order to define the nature and site of the disorder. Evidence points to an isolated impairment of urea elimination, giving rise to a reduced urea concentrating ability and thus to a decrease in maximum urine concentration and water conservation. The most probable site of this impairment seems to be the proximal tubule.

[Pseudohypoaldosteronism: a special form of sodium loss in infancy]

An infant with urinary sodium wasting is described. The plasma renin activity and plasma aldosterone concentration were distinctly raised. Administering DOCA was without effect. The condition pseudohypoaldosteronism is due to renal tubular unresponsiveness to endogenous aldosterone and can be adequately treated by salt replacement.

A new variant of Lowe oculocerebrorenal syndrome

A case is reported of a 5-year-old boy with Lowe syndrome. The patient was unusual in that he had only mild and transient acidosis with no rickets. The corneal opacities in the parents suggest that this disease might be autosomal recessive.

Haematological studies in a case of oculocerebrorenal syndrome

A four-year-old boy affected by oculocerebrorenal syndrome had moderate anaemia. The haematological study indicated hyperhaemolysis probably due to an extra-erythrocytic factor. It is suggested that this factor might be related to the metabolic disturbance of the disease, particularly the hyperchloraemic acidosis.

Familial hypouricaemia due to renal tubular defect of urate transport

A 28-year-old man was found to have hypouricaemia (plasma uric acid, 0.40 to 1.25 mg/100 ml). The 24-hour urinary urate excretion on a low purine diet was 690 mg, a value higher than the mean value of 419 mg for gouty Japanese patients. Urate clearance was 88.5 ml/min--approximately the same as the endogeneous creatinine clearance. The ratio of urate clearance to creatinine clearance was scarcely altered by pyrazinamide, but diminished by probenecid (from 69.2% to 52.4%). No other renal tubular abnormalities were detected. The findings in this subject may be accounted for by a nearly complete tubular defect in reabsorptive transport mechanisms of urate. A survey of his family revealed at least three similarly affected persons, who were all from consanguineous marriages. The hypouricaemia was transmitted as an autosomal trait.

Transport into erythrocytes and intestinal absorption of uric acid in hereditary renal hypouricemia

Uric acid transport into the erythrocytes and uric acid absorption from the intestine in a subject with hereditary defective renal tubular uric acid reabsorption was found to be normal. The findings are discussed in relation to the variability of phenotype expression in other renal tubular transport disorders.

Abnormal membrane sodium transport in Liddle's syndrome

We have documented the presence of abnormal sodium transport in Liddle's syndrome by measuring sodium concentration, sodium influx, and fractional sodium outflux in vitro in erythrocytes from normal subjects, two patients with Liddle's syndrome, and one patient with primary hyperaldosteronism. Sodium influx and fractional sodium outflux, but not sodium concentration, were significantly increased in patients with Liddle's syndrome. Sodium outflux in a patient with primary hyperaldosteronism did not differ significantly from normal. These alterations of sodium transport in erythrocytes from patients with Liddle's syndrome were not attributable to circulating levels of aldosterone, renin, angiotensin, or serum potassium. Furthermore, changes in aldosterone secretory rate and levels of circulating renin produced by varying dietary sodium intake, did not alter sodium influx or fractional sodium outflux in either patients with Liddle's syndrome or normal subjects. The response of fractional sodium outflux and sodium influx to ouabain, ethacrynic acid, and to changes in the cation composition of the incubation medium suggests that the increased sodium fluxes in Liddle's syndrome do not result solely from a quantitative increase in those components of sodium transport which occur in normal human erythrocytes. Instead, at least a portion of the increased erythrocyte sodium transport in Liddle's syndrome represents a component of sodium transport which does not occur in normal human erythrocytes.