ER ribosomal-binding protein 1 regulates blood pressure and potassium homeostasis by modulating intracellular renin trafficking.

BACKGROUND: Genome-wide association studies (GWASs) have linked RRBP1 (ribosomal-binding protein 1) genetic variants to atherosclerotic cardiovascular diseases and serum lipoprotein levels. However, how RRBP1 regulates blood pressure is unknown. METHODS: To identify genetic variants associated with blood pressure, we performed a genome-wide linkage analysis with regional fine mapping in the Stanford Asia-Pacific Program for Hypertension and Insulin Resistance (SAPPHIRe) cohort. We further investigated the role of the RRBP1 gene using a transgenic mouse model and a human cell model. RESULTS: In the SAPPHIRe cohort, we discovered that genetic variants of the RRBP1 gene were associated with blood pressure variation, which was confirmed by other GWASs for blood pressure. Rrbp1- knockout (KO) mice had lower blood pressure and were more likely to die suddenly from severe hyperkalemia caused by phenotypically hyporeninemic hypoaldosteronism than wild-type controls. The survival of Rrbp1-KO mice significantly decreased under high potassium intake due to lethal hyperkalemia-induced arrhythmia and persistent hypoaldosteronism, which could be rescued by fludrocortisone. An immunohistochemical study revealed renin accumulation in the juxtaglomerular cells of Rrbp1-KO mice. In the RRBP1-knockdown Calu-6 cells, a human renin-producing cell line, transmission electron and confocal microscopy revealed that renin was primarily retained in the endoplasmic reticulum and was unable to efficiently target the Golgi apparatus for secretion. CONCLUSIONS: RRBP1 deficiency in mice caused hyporeninemic hypoaldosteronism, resulting in lower blood pressure, severe hyperkalemia, and sudden cardiac death. In juxtaglomerular cells, deficiency of RRBP1 reduced renin intracellular trafficking from ER to Golgi apparatus. RRBP1 is a brand-new regulator of blood pressure and potassium homeostasis discovered in this study.

Thyrotoxic periodic paralysis in two sexagenarian men: A case report.

RATIONALE: Thyrotoxic periodic paralysis (TPP) characterized by the triad of muscle paralysis, acute hypokalemia, and the presence of hyperthyroidism is often reported in young adults but rarely reported in age >60 year-old. PATIENT CONCERNS: Two sexagenarian males (age 61 and 62) presenting to the emergency department with progressive muscle paralysis for hours. There was symmetrical flaccid paralysis with areflexia of lower extremities. Both of them did not have the obvious precipitating factors and take any drugs. DIAGNOSIS: Their Wayne scores, as an objective index of symptoms and signs associated with thyrotoxicosis, were <19 (7 and 14, respectively). Their blood pressure stood 162/78 and 170/82 mm Hg, respectively. Their thyroid glands were slightly enlarged. Both of them had severe hypokalemia (1.8 and 2.0 mmol/L). Their presumptive diagnosis of mineralocorticoid excess disorders with severe potassium (K+) deficit were made. However, low urine K+ excretion and relatively normal blood acid-base status were suggestive of an intracellular shift of K+ rather than K+ deficit. Hormone studies confirmed hyperthyroidism due to Graves disease. INTERVENTIONS: A smaller dose of K+ supplementation (only a total of 50 and 70 mmol K+, respectively) were prescribed for the patient. OUTCOMES: After treatment, their serum K+ levels became normal with a full recovery of muscle strength. LESSONS: Our 2 cases highlight the fact that thyrotoxic periodic paralysis must be still kept in mind as the underlying cause of hypokalemia with paralysis and hypertension in elderly patients to avoid missing curable disorders.

Hypokalemic paralysis in hyperthyroidism: Not all that glitter are gold.

Abnormal acid-base status (metabolic acidosis or alkalosis), inappropriate urine electrolytes excretion (high or low Na+ and Cl-), and higher required dose of potassium supplement (4-5 mmol/kg) are suggestive of non-TPP causes of hypokalemia.

Identification of the Causes for Chronic Hypokalemia: Importance of Urinary Sodium and Chloride Excretion.

BACKGROUND: Uncovering the correct diagnosis of chronic hypokalemia with potassium (K+) wasting from the kidneys or gut can be fraught with challenges. We identified clinical and laboratory parameters helpful for differentiating the causes of chronic hypokalemia. METHODS: Normotensive patients referred to our tertiary academic medical center for the evaluation of chronic hypokalemia were prospectively enrolled over 5 years. Clinical features, laboratory examinations-including blood and spot urine electrolytes, acid-base status, biochemistries, and hormones-as well as genetic analysis, were determined. RESULTS: Ninety-nine patients with chronic normotensive hypokalemia (serum K+ 2.8 ± 0.4 mmol/L, duration 4.1 ± 0.9 years) were enrolled. Neuromuscular symptoms were the most common complaints. Although Gitelman syndrome (n = 33), Bartter syndrome (n = 10), and distal renal tubular acidosis (n = 12) were the predominant renal tubular disorders, 44 patients (44%) were diagnosed with anorexia/bulimia nervosa (n = 21), surreptitious use of laxatives (n = 11), or diuretics (n = 12). Patients with gastrointestinal causes and surreptitious diuretics use exhibited a female predominance, lower body mass index, and less K+ supplementation. High urine K+ excretion (transtubular potassium gradient >3, urine K+/Cr >2 mmol/mmol) was universally present in patients with renal tubular disorders, but also found in >50% patients with gastrointestinal causes. Of interest, while urine sodium (Na+) and chloride (Cl-) excretions were high and coupled (urine Na+/Cl- ratio ∼1) in renal tubular disorders and "on" diuretics use, skewed or uncoupled urine Na+ and Cl- excretions were found in anorexia/bulimia nervosa and laxatives abuse (urine Na+/Cl- ratio: 5.0 ± 2.2, 0.4 ± 0.2, respectively) and low urine Na+ and Cl- excretions with fixed Na+/Cl- ratios (0.9 ± 0.2) when "off" diuretics. CONCLUSION: Besides body mass index, sex, and blood acid-base status, integrated interpretation of the urine Na+:Cl- excretion and their ratio is important to make an accurate diagnosis and treatment plan for patients with chronic normotensive hypokalemia.

Gitelman syndrome: consensus and guidance from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference.

Gitelman syndrome (GS) is a rare, salt-losing tubulopathy characterized by hypokalemic metabolic alkalosis with hypomagnesemia and hypocalciuria. The disease is recessively inherited, caused by inactivating mutations in the SLC12A3 gene that encodes the thiazide-sensitive sodium-chloride cotransporter (NCC). GS is usually detected during adolescence or adulthood, either fortuitously or in association with mild or nonspecific symptoms or both. The disease is characterized by high phenotypic variability and a significant reduction in the quality of life, and it may be associated with severe manifestations. GS is usually managed by a liberal salt intake together with oral magnesium and potassium supplements. A general problem in rare diseases is the lack of high quality evidence to inform diagnosis, prognosis, and management. We report here on the current state of knowledge related to the diagnostic evaluation, follow-up, management, and treatment of GS; identify knowledge gaps; and propose a research agenda to substantiate a number of issues related to GS. This expert consensus statement aims to establish an initial framework to enable clinical auditing and thus improve quality control of care.

CB1 cannabinoid receptor antagonist attenuates left ventricular hypertrophy and Akt-mediated cardiac fibrosis in experimental uremia.

Cannabinoid receptor type 1 (CB1R) plays an important role in the development of myocardial hypertrophy and fibrosis-2 pathological features of uremic cardiomyopathy. However, it remains unknown whether CB1R is involved in the pathogenesis of uremic cardiomyopathy. Here, we aimed to elucidate the role of CB1R in the development of uremic cardiomyopathy via modulation of Akt signalling. The heart size and myocardial fibrosis were evaluated by echocardiography and immunohistochemical staining, respectively, in 5/6 nephrectomy chronic kidney disease (CKD) mice treated with a CB1R antagonist. CB1R and fibrosis marker expression levels were determined by immunoblotting in H9c2 cells exposed to the uremic toxin indoxyl sulfate (IS), with an organic anion transporter 1 inhibitor or a CB1R antagonist or agonist. Akt phosphorylation was also assessed to examine the signaling pathways downstream of CB1R activation induced by IS in H9c2 cells. CKD mice exhibited marked left ventricular hypertrophy and myocardial fibrosis, which were reversed by treatment with the CB1R antagonist. CB1R, collagen I, transforming growth factor (TGF)-ß, and α-smooth muscle actin (SMA) expression showed time- and dose-dependent upregulation in H9c2 cells treated with IS. The inhibition of CB1R by either CB1R antagonist or small interfering RNA-mediated knockdown attenuated the expression of collagen I, TGF-ß, and α-SMA in IS-treated H9c2 cells, while Akt phosphorylation was enhanced by CB1R agonist and abrogated by CB1R antagonist in these cells. In summary, we conclude that CB1R blockade attenuates LVH and Akt-mediated cardiac fibrosis in a CKD mouse model. Uremic toxin IS stimulates the expression of CB1R and fibrotic markers and CB1R inhibition exerts anti-fibrotic effects via modulation of Akt signaling in H9c2 myofibroblasts. Therefore, the development of drugs targeting CB1R may have therapeutic potential in the treatment of uremic cardiomyopathy.

Implementing systems thinking for infection prevention: The cessation of repeated scabies outbreaks in a respiratory care ward.

BACKGROUND: Root cause analysis (RCA) is often adopted to complement epidemiologic investigation for outbreaks and infection-related adverse events in hospitals; however, RCA has been argued to have limited effectiveness in preventing such events. We describe how an innovative systems analysis approach halted repeated scabies outbreaks, and highlight the importance of systems thinking for outbreaks analysis and sustaining effective infection prevention and control. METHODS: Following RCA for a third successive outbreak of scabies over a 17-month period in a 60-bed respiratory care ward of a Taiwan hospital, a systems-oriented event analysis (SOEA) model was used to reanalyze the outbreak. Both approaches and the recommendations were compared. RESULTS: No nosocomial scabies have been reported for more than 1975 days since implementation of the SOEA. Previous intervals between seeming eradication and repeat outbreaks following RCA were 270 days and 180 days. Achieving a sustainable positive resolution relied on applying systems thinking and the holistic analysis of the system, not merely looking for root causes of events. CONCLUSION: To improve the effectiveness of outbreaks analysis and infection control, an emphasis on systems thinking is critical, along with a practical approach to ensure its effective implementation. The SOEA model provides the necessary framework and is a viable complementary approach, or alternative, to RCA.

Etiologic and therapeutic analysis in patients with hypokalemic nonperiodic paralysis.

BACKGROUND: Hypokalemic nonperiodic paralysis represents a group of heterogeneous disorders with a large potassium (K(+)) deficit. Rapid diagnosis of curable causes with appropriate treatment is challenging to avoid the sequelae of hypokalemia. We prospectively analyzed the etiologies and therapeutic characteristics of hypokalemic nonperiodic paralysis. METHODS: Over an 8-year period, patients with hypokalemic nonperiodic paralysis were enrolled by excluding those with hypokalemic periodic paralysis due to acute shift of K(+) into cells. Blood and spot urine samples were collected for the measurements of electrolytes, pH, and biochemistries. Intravenous potassium chloride (KCl) at a rate of 10-20 mmol/h was administered until muscle strength recovered. RESULTS: We had identified 58 patients with hypokalemic nonperiodic paralysis from 208 consecutive patients with hypokalemic paralysis, and their average K(+) concentration was 1.8 ± 0.2 mmol/L. Among patients with low urinary K(+) excretion (n = 17), chronic alcoholism, remote diuretic use, and anorexia/bulimia nervosa were the most common causes. Among patients with high urinary K(+) excretion (n = 41) and metabolic acidosis, renal tubular acidosis and chronic toluene abuse were the main causes, while primary aldosteronism, Gitelman syndrome, and diuretics were the leading diagnoses with metabolic alkalosis. The average KCl dose needed to restore muscle strength was 3.8 ± 0.8 mmol/kg. Initial lower plasma K(+), volume depletion, and high urinary K(+) excretion were associated with higher recovery KCl dosage. During therapy, patients with paradoxical hypokalemia (n = 32) who required more KCl supplementation than patients without (4.1 ± 0.7 vs 3.4 ± 0.7 mmol/kg, P < 0.001) often exhibited significantly higher plasma renin activity and received a higher volume of normal saline before its appearance. CONCLUSIONS: Understanding the common etiologies of hypokalemic nonperiodic paralysis may aid in early diagnosis. Patients with initial lower plasma K(+), renal K(+) wasting, and hypovolemia required higher recovery K(+) dosage. Paradoxical hypokalemia is prone to develop in hypovolemic patients even during K(+) supplementation with volume repletion.

Targeting tumour necrosis factor receptor 1 assembly reverses Th17-mediated colitis through boosting a Th2 response.

OBJECTIVE: The soluble preligand assembly domain (PLAD) of tumour necrosis factor receptor 1 (TNFR1) interferes with receptor trimerisation to block downstream signalling, and mediates Th17 suppression. We explored the therapeutic potential of recombinant PLAD.Fc protein on a spontaneous experimental colitis. DESIGN: A T-cell-specific BLIMP-1 knockout mouse model with mixed Th1/Th17 responses, resembling human Crohn's disease (CD) was established, and its colitogenic phenotype was characterised. Mice, 9 weeks old, were treated with PLAD.Fc protein at 5 mg/kg of body weight twice per week for 16 weeks, and presence of colitis was monitored by the appearance of diarrhoea, weight loss, and by histological colonic scoring. Activation status, cytokine profiles, and transcription factors in T cells were further analysed. RESULTS: The colitogenic phenotype in BLIMP-1 knockout mice was alleviated when an interleukin (IL)-23 knockdown transgene was introduced, indicating a therapeutic potential by downregulating IL-23-Th17 axis in these knockout mice. In PLAD.Fc-treated group, the mouse body weight remained stable and only mild disease scores were revealed. The percentage of naive CD4 T cells was increased and that of effector/memory CD4 T cells was decreased after PLAD.Fc-treatment. Moreover, the levels of IFN-γ, IL-17, IL-21, IL-22, IL-23R, granulocyte-macrophage colony-stimulating factor (GM-CSF) and TNF-α were diminished. Strikingly, Th2-associated cytokines (IL-4, IL-13 and IL-10) in sera, as well as percentages of Th2 cells, were increased in PLAD.Fc-treated mice. However, PLAD.Fc-mediated suppression of effector phenotypes in Th1/Th17 was abrogated after neutralising IL-10. CONCLUSIONS: The Th2 cytokine milieu induced by PLAD.Fc rebalanced T-helper cell subsets and conferred a protection against colitis in BLIMP-1 knockout mice.

Thyrotoxic periodic paralysis triggered by ß2-adrenergic bronchodilators.

Hypokalemic periodic paralysis is the most common form of periodic paralysis and is characterized by attacks of muscle paralysis associated with a low serum potassium (K+) level due to an acute intracellular shifting. Thyrotoxic periodic paralysis (TPP), characterized by the triad of muscle paralysis, acute hypokalemia, and hyperthyroidism, is one cause of hypokalemic periodic paralysis. The triggering of an attack of undiagnosed TPP by ß2-adrenergic bronchodilators has, to our knowledge, not been reported previously. We describe two young men who presented to the emergency department with the sudden onset of muscle paralysis after administration of inhaled ß2-adrenergic bronchodilators for asthma. In both cases, the physical examination revealed an enlarged thyroid gland and symmetrical flaccid paralysis with areflexia of lower extremities. Hypokalemia with low urine K+ excretion and normal blood acid-base status was found on laboratory testing, suggestive of an intracellular shift of K+, and the patients' muscle strength recovered at serum K+ concentrations of 3.0 and 3.3 mmol/L. One patient developed hyperkalemia after a total potassium chloride supplementation of 110 mmol. Thyroid function testing was diagnostic of primary hyperthyroidism due to Graves disease in both cases. These cases illustrate that ß2-adrenergic bronchodilators should be considered a potential precipitant of TPP.

Hypokalemic paralysis in a middle-aged female with classic Bartter syndrome.

Inherited classic Bartter syndrome (cBS) is an autosomal recessive renal tubular disorder resulting from inactivating mutations in the asolateral chloride channel (C1C-Kb) and usually presents in early infancy or childhood with mild to moderate hypokalemia. Profound hypokalemic paralysis in patients with cBS is extremely rare, especially in middle age. A 45-year-old Chinese female patient was referred for evaluation of chronic severe hypokalemia despite regular K+ supplementation (1 mmol/kg/d). She had had two episodes of muscle paralysis due to severe hypokalemia (K+ 1.9 - 2.1 mmol/l) in the past 3 years. She denied vomiting, diarrhea, or the use of laxatives or diuretics. Her blood pressure was normal. Biochemical studies showed hypokalemia (K+ 2.5 mmol/l) with renal potassium wasting, metabolic alkalosis (HCO3- 32 mmol/l), normomagnesemia (Mg2+ 0.8 mmol/l), hypercalciuria (calcium to creatinine ratio 0.5 mmol/mmol; normal < 0.22 mmol/mol), high plasma renin activity, but normal plasma aldosterone concentration. Abdominal sonography revealed neither renal stones nor nephrocalcinosis. Acquired causes of cBS such as autoimmune disease and drugs were all excluded. Molecular analysis of the CLCNKB gene, encoding ClC-Kb, and SLC12A3, encoding the thiazide-sensitive sodium chloride cotransporter (NCC), revealed compound heterozygous mutations in CLCNKB (L335P and G470E) inherited from her parents; her SLC12A3 was normal. These two mutations were not identified in 100 healthy subjects. Her plasma K+ concentration rose to 3 - 3.5 mmol/l after the addition of spironolactone. Inherited cBS may present with hypokalemic paralysis and should be considered in adult patients with hypokalemia and metabolic alkalosis.

Incidence and factors of post-adrenalectomy hyperkalemia in patients with aldosterone producing adenoma.

BACKGROUND: Hyperkalemia is a potentially serious complication following adrenalectomy of aldosterone-producing adenomas (APA). We analyzed the incidence and risk factors for hyperkalemia after adrenalectomy in patients with APA. METHODS: We retrospectively analyzed the records of 55 patients who underwent adrenalectomy for APA between 2002 and 2011. Demographic features, biochemical and hormonal profiles, imaging, and relevant medications were reviewed. RESULTS: Sixteen of 55 APA patients (29.1%) developed hyperkalemia (mean serum K(+) 5.6±0.3 mmol/l) after adrenalectomy and 3 had persistent hyperkalemia requiring mineralocorticoid supplementation for more than nine months. Compared with normokalemic patients, hyperkalemic patients were characterized by male predominance, older age, longer duration of hypertension (12.8±9.3 vs. 6.7±5.0 y, p<0.05), lower nadir serum K(+) (p<0.05), higher preoperative serum creatinine (p<0.01), and higher likelihood of residual hypertension. Using multivariate regression analysis, longer duration of hypertension and impaired renal function were the most important factors of post-adrenalectomy hyperkalemia. CONCLUSIONS: Post-adrenalectomy hyperkalemia in patients with APA is not rare and associated with impaired renal function and longer duration of hypertension. Serum K(+) must be cautiously monitored in patients with long-term hypertension and kidney disease.

A hypokalaemic woman with nephrocalcinosis: rebirth of old knowledge.

The coexistence of hypokalaemia and nephrocalcinosis poses a challenge in rapid diagnosis and appropriate management. We describe a 38-year-old woman who presented with thirst, intermittent carpopedal spasm, paresthaesia of both hands and progressive weakness of lower extremities for two years. She had a history of chronic hypokalaemia of unknown cause with intermittent potassium supplementation for 7-8 y and bilateral nephrocalcinosis notable for one year. She denied vomiting, diarrhoea or use of laxatives, alcohol or diuretics. Her blood pressure was normal. Laboratory investigations showed hypokalaemia (2.7 mmol/L) and metabolic alkalosis (HCO3(-) 32.6 mmol/L, pH 7.46). Two random urine samples both showed a consistently high urine K(+) excretion but with excretion rates of Na(+), Cl(-) and divalent cations which were high in one sample but not the other. Ingestion of furosemide 120 mg daily for body image for 7-8 y was uncovered. With furosemide cessation and potassium supplementation, her hypokalaemia with neuromuscular symptoms was corrected but nephrocalcinosis persisted. Surreptitious use of diuretics for various purposes should be kept in mind as an important cause of hypokalaemia and/or nephrocalcinosis. Measurement of electrolyte concentrations in at least two random urine samples is warranted to distinguish it from true renal tubular disorders and extrarenal causes.

Hypokalemic paralysis in a young obese female.

BACKGROUND: Profound hypokalemia with paralysis usually poses a diagnostic and therapeutic challenge. METHODS: We report on a 28-y-old obese Chinese female presenting with sudden onset of flaccid quadriparesis upon awaking in the morning. There is no family history of hyperthyroidism. She experienced body weight loss of 7 kg in 2 months. RESULTS: The most conspicuous blood biochemistry is marked hypokalemia (1.8 mmol/l) and hypophosphatemia (0.5 mmol/l) associated with low urine K(+) and phosphate excretion. Surreptitious laxatives and/or diuretics abuse-related hypokalemic paralysis were tentatively made. However, her relatively normal blood acid-base status and the absence of low urine Na(+) and/or Cl(-) excretion made these diagnoses unlikely. Furthermore, she developed rebound hyperkalemia (5.7 mmol/l) after only 80 mmol K(+) supplementation. Thyroid function test confirmed hyperthyroidism due to Graves' disease. Control of the hyperthyroidism completely abolished her periodic paralysis. CONCLUSIONS: Thyrotoxic periodic paralysis (TPP) should be kept in mind as a cause of paralysis in female, even with obesity, despite its predominance in adult males.

Refractory diffuse bony pain 20 years after jejunoileal bypass.

Osteomalacia can be a late but unrecognized complication following jejunoileal bypass. We describe a 53-year-old man who underwent jejunoileal bypass for morbid obesity twenty years earlier who suffered from progressive diffuse bony pain refractory to nonsteroidal anti-inflammatory drugs. He was initially diagnosed with a malignancy with bone metastasis. However, pertinent laboratory data were notable for hypocalcemia (7.5 mg/dL, albumin 4.1 mg/dL) with low urinary calcium excretion (14 mg/day), hypophosphatemia (2.0 mg/dL) with low urinary phosphate excretion (53 mg/day), hypomagnesemia (1.5 mg/dL) with low urine magnesium excretion (23 mg/day), low 1, 25 (OH)2 vitamin D3, and elevated serum alkaline phosphatase and intact parathyroid hormone (iPTH). These laboratory findings pointed to a defect in calcium, phosphate, and magnesium handling in the gastrointestinal tract. Bone biopsy of the iliac crest clearly demonstrated typical changes of osteomalacia with excessive osteoid accumulation and reduced mineralization. His clinical symptoms were refractory to oral 1, 25 (OH)2 vitamin D3 and calcium supplementation but significantly improved with the addition of intermittent intravenous active 1, 25 (OH)2 vitamin D3, calcium, phosphate, and magnesium supplementation. Osteomalacia is an easily misdiagnosed late complication of jejunoileal bypass. Early recognition can avoid circuitous diagnosis and inappropriate management.

Therapeutic analysis in Chinese patients with thyrotoxic periodic paralysis over 6 years.

OBJECTIVE: To characterize the course of therapy in a large cohort of Chinese patients with thyrotoxic periodic paralysis (TPP), a reversible electrolyte emergency fraught with therapeutic challenges. DESIGN AND METHODS: In this prospective interventional study, 78 patients with TPP (75 males and three females with an age range of 16-48 years) were consecutively enrolled over a 6-year period. Intravenous KCl at a rate of 10 mmol/h was administered until muscle strength recovered. Serum potassium (K(+)) and phosphorus concentrations were measured hourly during the paralytic attack and for 6 h after recovery. RESULTS: The serum potassium (K(+)) on attack was 2.1+/-0.2 mmol/l. The dose of KCl administered to restore muscle strength was 63+/-32 mmol, and peak serum K(+) concentration after recovery was 5.3+/-0.5 mmol/l. A paradoxical fall in serum K(+) concentration >0.1 mmol/l difference between presentation and treatment nadir was observed in approximately one-fourth of TPP patients (n=20). These patients had significantly higher serum-free thyroxine concentration, systolic blood pressure, and heart rate on presentation, as well as serum phosphate concentration on recovery. They not only needed much more KCl supplementation (104+/-34 vs 48+/-19 mmol, P<0.001), but also had significantly more severe rebound hyperkalemia (5.8+/-0.5 vs 5.1+/-0.4 mmol/l, P<0.001) on recovery than those who did not have paradoxical hypokalemia. There was a positive correlation between the dose of KCl administered and the difference between peak and nadir serum K(+) (Delta K(+)) (r=0.68, P<0.001). CONCLUSIONS: TPP patients who do not develop paradoxical hypokalemia need a smaller KCl dose to achieve recovery, whereas those who develop paradoxical hypokalemia have more severe hyperthyroidism and hyperadrenergic activity and may require blockage of intracellular K(+) shift to prevent rebound hyperkalemia.

Chronic renal failure in a boy with classic Bartter's syndrome due to a novel mutation in CLCNKB coding for the chloride channel.

BACKGROUND: Progressive renal failure in patients with classic Bartter's syndrome (cBS) due to inactivating mutations in CLCNKB gene is extraordinarily rare. DISCUSSION: We describe a 17-year-old Chinese boy who presented with progressive muscle weakness and renal failure. He was diagnosed as BS of unknown type at the age of 9 months and treated with indomethacin (2 mg/kg/day) and potassium chloride (KCl) supplementation (1.5 mEq/kg/day) for hypokalemia (2.5 mmol/l). At the age of 12 years, serum K+ was 3.0 mmol/l and creatinine reached 2.0 mg/dl. On admission, his blood pressure was normal but volume status was depleted. Urinalysis was essentially normal. Biochemical studies showed hypokalemia (K+ 2.4 mmol/l) with a high transtubular K+ gradient (TTKG) 9.6, metabolic alkalosis (HCO3- 28.4 mmol/l), normomagnesemia (2.0 mg/dl), severe renal failure (BUN 94 mg/dl, Cr 6.3 mg/dl), and hypocalciuria (urine calcium/creatinine ratio 0.02 mg/mg). Abdominal sonography revealed bilateral small size kidneys without nephrocalcinosis or renal stones. After the withdrawal of indomethacin with regular KCl and adequate fluid supplementation for 1 year, serum creatinine and K+ levels have been maintained at 4.0 mg/dl and 3.3 mmol/l, respectively. Direct sequencing of NKCC2, ROMK, ClC-Kb, and NCCT in this patient disclosed a novel homozygous missense mutation (GGG to GAG, G470E) in CLCNKB. This G470E mutation was not identified in 100 healthy Chinese subjects. Long-term therapy of non-steroidal anti-inflammatory drugs (NSAIDs), prolonged hypokalemia, chronic volume depletion, and underlying genetic variety may contribute to the deterioration of his renal function. The cautious use of NSAIDs, aggressive correction of hypokalemia, and avoidance of severe volume depletion may prevent the irreversible renal damage in patients with BS due to a Cl- channel defect.

Total parathyroidectomy without autotransplantation for secondary hyperparathyroidism.

BACKGROUND: To treat secondary hyperparathyroidism with subtotal parathyroidectomy or total parathyroidectomy with autotransplantation might cause the disease to recur because of growth of the parathyroid remnant or the autografts. The aim of the present study was to determinate an alternative surgical treatment for secondary hyperparathyroidism. METHODS: Of 94 uremic patients, 44 (median age: 50.5 years; 33 women/11 men) were assigned to group A, patients who were not expected to receive kidney transplantation for various reasons and had total parathyroidectomy without autotransplantation; 50 (median age 46 years; 33 women/17 men) were assigned to group B, patients who had either total parathyroidectomy with autotransplantation or subtotal total parathyroidectomy with preservation of parathyroid tissue in situ. Parameters measured included demographics, perioperative and follow-up biochemistry tests, operative time, postoperative complications, length of hospital stay, patients' compliance with the postoperative calcium and 1,25 dihydroxy-viatmin D supplementation regimen, symptom relief, and presence of recurrence. RESULTS: Mean operative times were 103 and 122 min (P = 0.007); postoperative complication rates were 18.2% and 12.0% (P = 0.563); mean hospital stays were 6 and 9 days (P = 0.259); adequate patient compliance with the postoperative calcium and 1,25 dihydroxy-viatmin D regimens were 84.1% and 78.0%, respectively (P = 0.6); symptom relief rates were 88.6% and 80.0% (P = 0.277). Recurrence rates over 60 months in group A and group B were 4.5% and 18.0%, resectively (P = 0.028 by Kaplan-Meier analysis). CONCLUSIONS: Because of the lower recurrent rate and shorter operative time, total parathyroidectomy without autotransplantation may be an option for treating patients with symptomatic secondary hyperparathyroidism who are not expected to receive kidney transplantation.

Recurring paralysis.

A 22-year-old Chinese man presented with sudden onset of generalised muscular weakness and paralysis upon awakening in the morning, due to sporadic periodic paralysis (SPP), a type of hypokalaemic periodic paralysis (HPP) without hyperthyroidism or familial history of paralysis. Laboratory studies showed marked hypokalaemia (K(+) 1.6 mmol/litre). He received intravenous KCl supplementation at a rate of 0.14 mmol/kg/h and developed a paradoxical fall in serum K(+) concentration from 1.6 to 1.4 mmol/litre during KCl therapy. After 160 mmol KCl supplementation his muscular strength recovered, but muscular paralysis recurred 2 h later. Acute recurrent hypokalaemia was the presumptive initial diagnosis and intravenous KCl supplementation was briefly reinitiated. Despite no obvious abnormalities on ECG monitoring, a 12-lead ECG clearly demonstrated tented T waves in the precordial leads suggestive of hyperkalaemia, later found to be 6.9 mmol/litre. After treatment with intravenous calcium gluconate, insulin and loop diuretics, his serum K(+) concentration fell to 4.7 mmol/litre and muscular paralysis resolved in 3 h.