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A 31-year-old woman with no significant past medical or family history was admitted with complaints of general weakness. Laboratory tests revealed: serum potassium 3.0 mEq/L, arterial blood pH 7.28, serum bicarbonate 17.8 mEq/L and urinary pH 7.0. Double-labeling confocal fluorescence microscopy using H(+)-ATPase and pendrin antibodies demonstrated a decreased expression of these proteins in the patient's renal collecting duct compared to normal controls. Anti-Sjögren's-syndrome-related antigen A (Anti-Ro/SS-A) and anti-Sjögren's syndrome type B (anti-La/SS-B) antibodies were strongly positive with very high titers, consistent with Sjögren's syndrome. We present a case of distal renal tubular acidosis-associated Sjögren's syndrome with a defect in H(+)-ATPase and pendrin in the renal collecting duct.

Background: In the chronic kidney disease (CKD) population, the impact of serum potassium (sK) on renal outcomes has been controversial. Moreover, the reasons for the potential prognostic value of hypokalemia have not been elucidated., Design Participants & Measurements: 2500 participants with CKD stage 1-4 in the Integrated CKD care program Kaohsiung for delaying Dialysis (ICKD) prospective observational study were analyzed and followed up for 2.7 years. Generalized additive model was fitted to determine the cutpoints and the U-shape association between sK and end-stage renal disease (ESRD). sK was classified into five groups with the cutpoints of 3.5, 4, 4.5 and 5 mEq/L. Cox proportional hazard regression models predicting the outcomes were used., Results: The mean age was 62.4 years, mean sK level was 4.2±0.5 mEq/L and average eGFR was 40.6 ml/min per 1.73 m(2). Female vs male, diuretic use vs. non-use, hypertension, higher eGFR, bicarbonate, CRP and hemoglobin levels significantly correlated with hypokalemia. In patients with lower sK, nephrotic range proteinuria, and hypoalbuminemia were more prevalent but the use of RAS (renin-angiotensin system) inhibitors was less frequent. Hypokalemia was significantly associated with ESRD with hazard ratios (HRs) of 1.82 (95% CI, 1.03-3.22) in sK <3.5mEq/L and 1.67 (95% CI,1.19-2.35) in sK = 3.5-4 mEq/L, respectively, compared with sK = 4.5-5 mEq/L. Hyperkalemia defined as sK >5 mEq/L conferred 1.6-fold (95% CI,1.09-2.34) increased risk of ESRD compared with sK = 4.5-5 mEq/L. Hypokalemia was also associated with rapid decline of renal function defined as eGFR slope below 20% of the distribution range., Conclusion: In conclusion, both hypokalemia and hyperkalemia are associated with increased risk of ESRD in CKD population. Hypokalemia is related to increased use of diuretics, decreased use of RAS blockade and malnutrition, all of which may impose additive deleterious effects on renal outcomes.

Background: Chronic hypokalemia has been associated with renal hypertrophy, interstitial disease, and hypertension in both adult animals and humans. However, the effects of potassium (K(+)) depletion on the rapidly growing infant have not been well studied. The purpose of this study was to determine the effects of severe chronic dietary K(+) depletion on blood pressure (BP) and renal structural changes in young rats., Methods: Sprague-Dawley rats (50 +/- 5 g) were fed either a control or a potassium-deficient diet (<0.05% K(+)) for 14 to 21 days. At the end of this period, the blood pressure (BP) was measured in all rats, and six rats in each group were sacrificed to determine changes in renal histology and renin-angiotensin system (RAS) activity. The remaining rats in each group were then switched to a high-salt (6% NaCl)--normal-K(+) (0.5%) diet or were continued on their respective control or K(+)-deficient diet for an additional six days. Blood pressure measurements were done every three days until the end of the study., Results: K(+)-depleted animals had significant growth retardation and increased RAS activity, manifested by high plasma renin activity, recruitment of renin-producing cells along the afferent arterioles, and down-regulation of angiotensin II receptors in renal glomeruli and ascending vasa rectae. K(+)-depleted kidneys also showed tubulointerstitial injury with tubular cell proliferation, osteopontin expression, macrophage infiltration, and early fibrosis. At week 2, K(+)-depleted rats had higher systolic BP than control rats. Switching to a high-salt (6% NaCl)--normal-K(+) diet resulted in further elevation of systolic BP in K(+)-depleted rats, which persisted even after the serum K(+) was normalized., Conclusion: Dietary potassium deficiency per se increases the BP in young rats and induces salt sensitivity that may involve at least two different pathogenic pathways: increased RAS activity and induction of tubulointerstitial injury.

Morphological changes were studied in the kidney of a potassium depleted 21-year old Japanese male with Bartter's syndrome. Characteristic features were PAS-positive intracytoplasmic granules in the inner medulla and the papilla. The intracytoplasmic granules were conspicuous towards the papillary tip and ultrastructurally composed of small vesicles, vacuoles, amorphous dense materials, lamellar contents and myelin like figures, and bounded by a single limiting membrane. The granules in this human kidney were, with regard to their distribution and ultrastructural findings, similar to those in the kidney of experimentally potassium depleted rats. The results indicate that the intracytoplasmic granules in the renal inner medulla and the papilla are the characteristic feature of the potassium depleted human kidney and a counterpart to those in the potassium depleted rat.

Renal biopsies from 40 patients with hypokalemia and hyponatremia of an average of 10 years' duration due to abuse of laxatives or diuretics, anorexia nervosa, or chronic vomiting were examined with morphometric methods. Light microscopy revealed the following alterations in the renal cortex as compared with 36 normal kidney: JGC were sometimes slightly and sometimes enormously enlarged (mean, 217%). Smaller glomeruli were found with reduction in the area of the glomerular capillaries and of Bowman's capsule (+/- 7%) but an increase in the area of the mesangial matrix by 25%. The proximal and distal tubules contained nonspecific vacuoles in only 8 of 40 biopsy specimens. Only minor, age-dependent arteriolosclerosis was demonstrable. In 75% of the cases, the interstitial surface area was increased (by 107%) with predominantly focal lymphocytic cellular infiltration. Interstitial fibrosis was more pronounced in emaciated patients. The morphologic-functional correlation between the increase of interstitial surface area and the rise in serum creatinine concentration was highly significant. Typical kaliopenic nephropathy is therefore detectable by light microscopy. GFR impairment correlates with the extent of interstitial fibrosis.

An electron microscopic comparison was made of intracellular granules of the renal papilla and inner medulla in two types of potassium depletion: one in a 47-year-old white male with chronic potassium-wasting renal disease and the other in the experimentally depleted rat. The granules in both cases were composed of small and large vesicles; myelin figures; small particles; and dense bodies, with a partial, or complete, single limiting membrane. Ultrastructurally, the constituent elements of the granules were essentially the same in the two types of potassium depletion. It was concluded that the intracellular granules in the human tissue were the result of potassium depletion and a counterpart to those in the potassium-depleted rat.

Morphologic alterations and membrane metabolism were studied in the kidneys of rats fed a low potassium diet. Transmission and scanning electron microscopy following perfusion-fixation of kidneys revealed that the earliest morphologic change occurs in cells of the papillary tip in which multivesicular bodies, a specific type to lysosome, appear after 1 day. Increased depletion leads to extension of the lesion to all cells of the papilla. After 1 week, a narrow band of hyperplasia in the inner red medulla appears; this band is characterized by adenomatous proliferation of intercalated and light cells and partial obstruction of collecting tubules. These alterations and cortical growth in the normal pattern result in increased renal weight. New membrane formation for lysosomes and growing cells was studied by measuring the rate of [14C]choline incorporation into phospholipid in slices from five zones of the kidney. In the papilla the rate increased 39 per cent after 18 hours, the earliest change detected. After 36 hours the rate increased in inner red medulla by 28 per cent, inner cortex by 25 per cent and outer cortex by 40 per cent. [14C]choline was a specific precursor of the three renal phospholipids, phosphatidylcholine, lysophosphatidylcholine, and sphingomyelin. The relative distribution of the label did not change with growth induced by potassium depletion. The results indicate that potassium depletion induces early increases in the formation of cell membrane phospholipid which correlate with specific morphologic changes in different zones within the kidney.