The kidney in potassium depletion

Mechanistic insights into the primary and secondary alterations of renal ion and water transport in the distal nephron

The kidneys, by equilibrating the outputs to the inputs, are essential for maintaining the constant volume, pH, and electrolyte composition of the internal milieu. Inability to do so, either because of internal kidney dysfunction (primary alteration) or because of some external factors (secondary alteration), leads to pathologies of varying severity, leading to modification of these parameters and affecting the functions of other organs. Alterations of the functions of the collecting duct (CD), the most distal part of the nephron, have been extensively studied and have led to a better diagnosis, better management of the related diseases, and the development of therapeutic tools. Thus, dysfunctions of principal cell-specific transporters such as ENaC or AQP2 or its receptors (mineralocorticoid or vasopressin receptors) caused by mutations or by compounds present in the environment (lithium, antibiotics, etc.) have been demonstrated in a variety of syndromes (Liddle, pseudohypoaldosteronism type-1, diabetes insipidus, etc.) affecting salt, potassium, and water balance. In parallel, studies on specific transporters (H⁺ -ATPase, anion exchanger 1) in intercalated cells have revealed the mechanisms of related tubulopathies like distal renal distal tubular acidosis or Sjögren syndrome. In this review, we will recapitulate the mechanisms of most of the primary and secondary alteration of the ion transport system of the CD to provide a better understanding of these diseases and highlight how a targeted perturbation may affect many different pathways due to the strong crosstalk and entanglements between the different actors (transporters, cell types).

High incidence of hypertension-mediated organ damage in a series of Chinese patients with 17α-hydroxylase deficiency

OBJECTIVE

To analyze the prevalence of hypertension-mediated organ damage (HMOD) and its relationship with enzyme activity of mutant CYP17A1 and other risk factors in patients with 17α-hydroxylase/17,20-lyase deficiency (17-OHD).

METHODS

A total of 68 patients with 17-OHD were recruited in the Peking Union Medical College Hospital from 2003 to 2021. The incidence of hypertension and HMOD was respectively analyzed. CYP17A1 sequencing was performed and the enzyme activity of mutant CYP17A1 was determined by analyzing the characteristics of mutation itself and the functional data reported previously. A logistic regression model was employed to analyze the factors related to HMOD and the specific damaged organs in 17-OHD patients.

RESULT(S)

Sixty-five patients (95.6%) exhibited hypertension, 32 of whom were diagnosed with HMOD. c.985_987delTACinsAA (p.Y329KfsX418) (53.8%) and c.1459_1467del (p. del D487_F489) (11.4%) were the top two mutations, and no correlation was found between enzyme activity of mutant CYP17A1 and HMOD. The risk of HMOD increased by 32% for each additional year of hypertension duration, 10.2-fold for each one-grade increase in hypertension level, 2.3-fold for each grade of exacerbation of hypokalemia.

CONCLUSION

Patients with 17-OHD experience a high incidence of HMOD. There was no correlation between the HMOD occurrence and enzyme activity of mutant CYP17A1. Longer duration of hypertension, more severe hypertension, and hypokalemia were independent risk factors for the occurrence of HMOD in patients with 17-OHD.

Primary Aldosteronism: Changing Definitions and New Concepts of Physiology and Pathophysiology Both Inside and Outside the Kidney

In the 60 years that have passed since the discovery of the mineralocorticoid hormone aldosterone, much has been learned about its synthesis (both adrenal and extra-adrenal), regulation (by renin-angiotensin II, potassium, adrenocorticotrophin, and other factors), and effects (on both epithelial and nonepithelial tissues). Once thought to be rare, primary aldosteronism (PA, in which aldosterone secretion by the adrenal is excessive and autonomous of its principal regulator, angiotensin II) is now known to be the most common specifically treatable and potentially curable form of hypertension, with most patients lacking the clinical feature of hypokalemia, the presence of which was previously considered to be necessary to warrant further efforts towards confirming a diagnosis of PA. This, and the appreciation that aldosterone excess leads to adverse cardiovascular, renal, central nervous, and psychological effects, that are at least partly independent of its effects on blood pressure, have had a profound influence on raising clinical and research interest in PA. Such research on patients with PA has, in turn, furthered knowledge regarding aldosterone synthesis, regulation, and effects. This review summarizes current progress in our understanding of the physiology of aldosterone, and towards defining the causes (including genetic bases), epidemiology, outcomes, and clinical approaches to diagnostic workup (including screening, diagnostic confirmation, and subtype differentiation) and treatment of PA.

Laxative abuse, eating disorders, and kidney stones: a case report and review of the literature

Kidney stones are listed among the complications of eating disorders; however, very few cases have been reported. We present an additional case of nephrolithiasis associated with laxative abuse, including detailed results of the patient's urine metabolic profiles, in a patient with idiopathic hypercalciuria. We review the literature and provide an explanation for the paucity of cases of nephrolithiasis associated with these disorders. Despite low urine volumes resulting from extracellular fluid volume depletion and hypocitraturia resulting from hypokalemia, both of which would tend to favor the formation of kidney stones, most patients with eating disorders are likely to be protected from stone formation by the hypocalciuric effect of extracellular fluid volume depletion and increased proximal tubular sodium reabsorption. However, patients with underlying idiopathic hypercalciuria who develop eating disorders may be at increased risk of stone formation in the setting of low urine volume and therefore high supersaturation of calcium oxalate and phosphate.

Does hypokalaemia cause nephropathy? An observational study of renal function in patients with Bartter or Gitelman syndrome

BACKGROUND

Hypokalaemic nephropathy has been described in patients with chronic potassium depletion; it is a condition in which proximal tubular vacuolization and interstitial fibrosis occur, resulting in a decline in glomerular filtration rate (GFR) and, in some cases, renal failure. It has been described in patients with chronic diarrhoea, eating disorders, laxative abuse and primary hyperaldosteronism; also occasionally in Bartter syndrome (BS), in which severe hypokalaemia accompanies significant renal sodium and water losses, though rarely in Gitelman syndrome (GS), in which there is equally severe hypokalaemia, but only modest sodium losses.

AIM

We hypothesized that hypokalaemic nephropathy may not be due to potassium depletion per se, but persistently elevated circulating levels of aldosterone, possibly with superimposed episodes of renal hypoperfusion.

DESIGN AND METHODS

We searched UK and European data sets to retrospectively compare serum and urinary parameters in patients with GS and BS.

RESULTS

The patients with GS often had lower serum potassium concentrations than patients with BS, but the BS patients had significantly higher serum creatinine concentrations and lower estimated GFRs (eGFR). BS patients had significantly higher fractional excretions of sodium compared with GS patients, as well as higher plasma renin activities and serum aldosterone levels.

CONCLUSION

These findings show that in genetically confirmed cases of BS and GS, the degree of hypokalaemia (as an index of chronic potassium depletion) does not correlate with GFR, and that on-going sodium and water losses, and consequent secondary hyperaldosteronism, may play a more important role in the aetiology of hypokalaemic nephropathy.

Potassium maintenance. Potassium supplements or potassium sparing agents

This paper reviews and presents data from a series of studies evaluating the extent of potassium depletion that occurs in various disease states and a comparison of the efficacy of potassium supplementation or potassium sparing diuretics in its correction. Changes in serum potassium levels are common after diuretics but are relatively minor in most people if small doses of diuretics are used. Total body potassium deficit is uncommon in people treated with a diuretic for hypertension and the fall in serum potassium results from alkalosis and a shift of potassium into the cell. Potassium sparing diuretics correct the potassium abnormality more readily than potassium supplements. Evidence is also presented that suggests that a high salt, low potassium diet may be an important cause of hypokalemia in people given diuretics.

Expression of urea transporters in potassium-depleted mouse kidney

Urea transport in the kidney is mediated by a family of transporter proteins that include the renal urea transporter (UT-A) and the erythrocyte urea transporter (UT-B). The purpose of this study was to determine the location of the urea transporter isoforms in the mouse kidney and to examine the effects of prolonged potassium depletion on the expression and distribution of these transporters by ultrastructural immunocytochemistry. C57BL6 mice were fed a low-potassium diet for 2 wk, and control animals received normal chow. After 2 wk on a low-potassium diet, urinary volume increased and urinary osmolality decreased (833 +/- 30 vs. 1,919 +/- 174 mosmol/kgH2O), as previously demonstrated. Kidneys were processed for immunocytochemistry with antibodies against UT-A1 (L446), UT-A1 and UT-A2 (L194), UT-A3 (Q2), and UT-B. In normal mice, UT-A1 and UT-A3 were expressed mainly in the cytoplasm of the terminal inner medullary collecting duct (IMCD). UT-A2 immunoreactivity was observed mainly on the basolateral membrane of the type 1 epithelium of the descending thin limb (DTL) of short-looped nephrons. The intensity of UT-A1 and UT-A3 immunoreactivity in the IMCD was markedly reduced in potassium-depleted mice. In contrast, there was a significant increase in UT-A2 immunoreactivity in the DTL. The intensity of UT-B immunoreactivity in the descending vasa recta (DVR) was reduced in potassium-depleted animals compared with controls. In control animals, UT-B immunoreactivity was predominantly observed in the plasma membrane, whereas in potassium-depleted mice, it was mainly observed in cytoplasmic granules in endothelial cells of the DVR. In summary, potassium depletion is associated with reduced expression of UT-A1, UT-A3, and UT-B but increased expression of UT-A2. We conclude that reduced expression of urea transporters may play a role in the impaired urine-concentrating ability associated with potassium deprivation.

Possible liposomal amphotericin B-induced nephrogenic diabetes insipidus

OBJECTIVE

To report the development of nephrogenic diabetes insipidus (NDI) associated with the use of high-dose liposomal amphotericin B.

CASE SUMMARY

A 38-year-old white man with relapsed acute myelogenous leukemia underwent a matched unrelated donor allogeneic bone marrow transplant with adequate engraftment and mild graft-versus-host disease responding to corticosteroids. Approximately 11 months after transplant, the patient was admitted to the hospital with suspected fungal pneumonia and started on liposomal amphotericin B (baseline serum creatinine 1.4-1.5 mg/dL). The dose was increased due to his immunosuppression and poor response, as the fungal etiology was identified as Torulopsis glabrata. The patient required mechanical ventilation due to biopsy-proven bronchiolitis olbiterans organizing pneumonia. Additionally, he developed diffuse alveolar hemorrhage and received intravenous desmopressin, with a reduction in bloody secretions. He also developed hypernatremia (serum sodium 155 mEq/L) on day 3 of the desmopressin and had an inappropriately increased urine output consistent with NDI. The most likely etiology for the NDI was liposomal amphotericin B and its associated hypokalemia.

DISCUSSION

The observation of worsening hypernatremia (serum sodium increased from 135 to 164 mEq/L) with polyuria was associated with an increasing cumulative dosage of liposomal amphotericin B for fungal pneumonia despite the concurrent use of intravenous desmopressin. Aggressive water replacement was an effective treatment option in this patient. The Naranjo probability scale classified this as a possible adverse reaction because of the temporal sequence of NDI after high-dose liposomal amphotericin B and previously reported cases of NDI associated with amphotericin B desoxycholate.

CONCLUSIONS

Amphotericin B desoxycholate has been implicated as an etiology for NDI, and the use of the newer liposomal amphotericin B reportedly avoids this rare complication. We observed the development of NDI despite the use of liposomal amphotericin B in a critically ill patient with bone marrow transplant.

Impairment of AVP regulation in 17alpha-hydroxylase deficiency, a unique form of adrenal insufficiency

17alpha-hydroxylase deficiency (17alpha-OHDS) results in decreased production of cortisol and sex steroids and hypokalemia secondary to excess mineralocorticoids. It has long been known that glucocorticoid deficiency is associated with impaired urinary dilution and increased secretion of vasopressin (AVP). On the other hand, chronic hypokalemia is a well-established cause of nephrogenic diabetes insipidus. We evaluated the status of AVP secretion in a patient with 17alpha-OHDS and in 8 normokalaemic control subjects during hypertonic saline infusion (5% NaCl 0.06 ml.kg.min.120 min). The patient was evaluated on 3 separate occasions: pre-treatment (PT), and daily treatment with 0.375 mg (T1) and 0.5 mg (T2) dexamethasone. Blood was collected for AVP, corticosterone (B), plasma osmolality (pOsm) and electrolyte determination. In the control group plasma AVP levels increased from 0.8 +/- 0.1 to 4.1 +/- 0.6 pmol/l and pOsm increased from 282 +/- 2 to 302 +/- 11.5 mosmol/kg. In the patient, plasma AVP levels increased from 9.3 to 12.3; 4.5 to 6.2; and 2.5 to 6.2 pmol/l, and pOsm increased from 282 to 302, from 290 to 307, and from 291 to 311 mosmol/kg during the PT, T1 and T2 conditions, respectively. Serum potassium levels were low (2.6 mmol/l) during PT and reached normal values after treatment. There was a significant negative correlation between plasma AVP and serum potassium levels (r=-0.71; p<0.001). The results originally indicate that high plasma AVP levels may be found in 17alpha-OHDS, suggesting an effect of F deficiency per se. In addition, a concealed partial nephrogenic diabetes insipidus secondary to chronic hypokalemia cannot be excluded.

The role of growth factors and ammonia in the genesis of hypokalemic nephropathy

Hypokalemia is a common electrolyte abnormality encountered in clinical practice. It can be identified in an asymptomatic patient undergoing routine electrolyte screening or can manifest itself as part of a number of functional abnormalities in a variety of organs and systems. Among the most commonly recognized complications are profound effects on the cardiovascular and neuromuscular systems, together with abnormalities in acid-base regulation. In humans, hypokalemia contributes to the development of hypertension and predisposes patients to a variety of ventricular arrhythmias, including ventricular fibrillation. Commonly recognized neuromuscular complications include weakness, cramping, and myalgia. Hypokalemia also affects systemic acid-base homeostasis by interfering with multiple components of the renal acid-base regulation and is a frequent cause of metabolic alkalosis. Less known, however, is the role of potassium deficiency in causing progressive renal failure. In animals, potassium deficiency stimulates renal enlargement because of cellular hypertrophy and hyperplasia. If potassium deficiency persists, interstitial infiltrates appear in the renal interstitial compartment, and eventually tubulointerstitial fibrosis develops. In humans, longstanding hypokalemia is associated with the development of renal cysts, chronic interstitial nephritis, and progressive loss of renal function, the so-called hypokalemic nephropathy. This review focuses on the potential mechanisms involved in the development of the hypokalemic nephropathy with emphasis on the role of ammonia and growth factors in its pathogenesis.

Early polyuria and urinary concentrating defect in potassium deprivation

The time course of the onset of nephrogenic diabetes insipidus and its relationship to aquaporin-2 (AQP2) expression in K(+) deprivation (KD) remains unknown. Rats were fed a K(+)-free diet and killed after 12 h, 1, 2, 3, 6, or 21 days. Serum K(+) concentration was decreased only after, but not before, 3 days of a K(+)-free diet. Urine osmolality, however, decreased as early as 12 h of KD (1,061 +/- 26 vs. 1,487 +/- 102 mosmol/kgH(2)O in control, P < 0.01). It decreased further at 24 h (to 858 +/- 162 mosmol/kgH(2)O in KD, P < 0.004) and remained low at 21 days of KD (436 +/- 58 mosmol/kgH(2)O, P < 0.0001 compared with baseline). Water intake decreased at 12 h (P < 0.002) but increased at 24 h (P < 0.05) and remained elevated at 21 days of KD. Urine volume increased at 24 h of KD (8 +/- 2 to 15 +/- 2 ml/24 h, P < 0.05) and remained elevated at 21 days. Immunoblot analysis demonstrated that AQP2 protein abundance in the outer medulla remained unchanged at 12 h (P > 0.05), decreased at 24 h ( approximately 44%, P < 0.001), and remained suppressed ( approximately 52%, P < 0.03) at 21 days of KD. In the inner medulla the AQP2 protein abundance remained unchanged at both 12 and 24 h of KD. AQP2 protein abundance in the cortex, however, decreased at 12 h ( approximately 47%, P < 0.01) and remained suppressed at 24 h ( approximately 77%, P < 0.001) of KD. Northern blot analysis showed that AQP2 mRNA decreased as early as 12 h of KD in both cortex (P < 0.02) and outer medulla (P < 0.01) and remained suppressed afterward. In conclusion, the urinary concentrating defect in KD is an early event and precedes the onset of hypokalemia. These studies further suggest that the very early urinary concentrating defect in KD (after 12 but before 24 h) results primarily from the suppression of cortical AQP2, whereas the later onset of a urinary concentrating defect (after 24 h) also involves a downregulation of medullary AQP2.

Potassium depletion downregulates chloride-absorbing transporters in rat kidney

Potassium depletion (KD) causes renal chloride wasting, suggesting defect(s) in Cl- reabsorption in renal tubules. To determine whether alterations in expression of the major Cl- transporter genes might contribute to the chloride wasting, we analyzed their expression in renal cortex and medulla of animals placed on KD diet. Feeding KD diet to rats resulted in significant hypokalemia at 14 d but not at 6 d. Northern hybridization revealed that mRNA levels for the apical Na-K-2Cl cotransporter in the medulla decreased by 56 and 51% at 6 and 14 d of KD diet, respectively. Functional studies in tubular suspensions from medullary thick ascending limb demonstrated that the Na-K-2Cl cotransporter activity decreased by approximately 45 and approximately 37% at 6 and 14 d of KD diet, respectively. mRNA levels for the thiazide-sensitive Na-Cl cotransporter decreased by 57 and 64% at 6 and 14 d of KD diet. Decreased expression of the apical Na-Cl and the Na-K-2Cl cotransporters became evident at 48 and 72 h of KD, respectively. Urinary chloride excretion increased at 48 h and further increased at 72 h of KD, correlating with suppression of the Na-Cl and the Na-K-2Cl transporters. Our results indicate that increased urinary chloride loss in KD results from suppression of the chloride-absorbing transporters. Downregulation of chloride transporters in KD is an early event and can lead to hypochloremia and subsequently hypovolemia and decreased glomerular filtration rate.

Acute renal failure associated with immunoglobulin therapy

Four cases of acute renal failure induced by intravenous immunoglobulin are presented, and the literature on the subject is reviewed. The clinical course varies from asymptomatic serum creatinine elevation to anuric renal failure occurring within days of the institution of therapy, followed by the rapid recovery of renal function after termination of therapy. The renal histology demonstrates severe tubular vacuolization with cellular swelling and preservation of the brush border. Glomerular endothelial, mesangial, and epithelial cells also may demonstrate swelling and vacuolization. There is no evidence for inflammatory or immune complex-mediated etiologies. The immunoglobulins or carbohydrate additives in the preparations appear to have a unique and reversible effect on the glomerular and tubular cell function.

Renal ammoniagenesis in humans with chronic potassium depletion

Renal ammonia production and distribution and ammonia precursor utilization were evaluated in eight patients with chronic potassium depletion (CPD) and aldosterone-producing adenoma and in 20 controls. In CPD, urinary ammonia excretion and ammonia added to renal venous blood were about twofold higher than in controls; thus, total ammonia production was significantly augmented (88.0 +/- 10.3 mumol/min.1.73 m2 vs. 45.0 +/- 2.6 in controls). Total ammonia production was inversely correlated with serum potassium and directly correlated with urine flow. Stepwise multiple regression analysis showed that both factors, mainly serum potassium, significantly influence ammonia production and account for 61.4% of variations in ammonia production. Renal extraction of glutamine was significantly increased (56.6 +/- 5.9 mumol/min.1.73 m2 vs. 34.6 +/- 3.1 in controls), and this could account for ammonia production. The ratio of urinary ammonia excretion to total ammonia production, an index of the intrarenal ammonia distribution, was similar in patients and controls, and was significantly correlated with urine pH and true renal blood flow (RBF). Stepwise multiple regression analysis showed that RBF, urine pH and urine flow also significantly affected ammonia distribution. However, these factors accounted for only 41.7% of variations in intrarenal ammonia partition, urine pH having a minor role. We conclude that in patients with CPD other factors besides urine pH, urine flow and RBF intervene in the ammonia partition between urine and blood.

Therapeutic results of primary aldosteronism with special reference to renal or renovascular lesions

A study was made of 9 patients with primary aldosteronism due to aldosterone-producing adenoma (APA) and 8 subjects with idiopathic adrenal hyperplasia (IHA) to clarify the pathogenesis of sustained hypertension after surgical or non-surgical treatment. Following each treatment, a complete improvement of hypertension was obtained in 12 patients (6 APA, 6 IHA), while 5 (3 APA, 2 IHA) showed still hypertensive status. Renal or renovascular lesions were prominent only in the hypertension-unchanged group. Under regular sodium diet, the ratio of urinary excretion of sodium to creatinine of this hypertensive group was significantly lower than that of the hypertension-improved group. However, the results of other renal function tests were similar in both groups. After respective treatments, suppressed plasma renin activity and elevated plasma aldosterone concentration were improved in all patients. In addition, patients of both groups showed normal response of the renin-aldosterone system following diuretic and dietary induced sodium and volume depletion. Based on these findings, renal or renovascular lesions appear to play an important role in the pathogenesis of maintenance of hypertension in this disorder after respective treatments.

Hypokalemic nephropathy in the rat. Role of ammonia in chronic tubular injury

Chronic potassium deficiency results in progressive tubulointerstitial injury, associated with augmented renal ammoniagenesis. We investigated the role of elevated renal ammonia levels and the interaction of ammonia with the complement system in this injury. Potassium deficiency was induced in rats by feeding a low potassium diet. Experimental animals received 150 mM NaHCO3 or equimolar NaCl, as drinking water. After 3 wk, NaHCO3 supplemented rats demonstrated decreased ammonia production, less renal hypertrophy, less histologic evidence of injury, and less proteinuria. In in vitro studies on normal cortical tubular fragments, the addition of ammonia to serum in concentrations comparable to renal cortical levels in potassium-deficient animals significantly increased tubular deposition of C3 as quantitated by a radiolabeled antibody binding technique. Thus, alkali supplementation reduced chronic tubulointerstitial disease in a rat model of hypokalemic nephropathy. We propose that increased cortical ammonia levels contribute to hypokalemic nephropathy through ammonia-mediated activation of the alternative complement pathway.

Intra- and inter-nephron heterogeneity of ammoniagenesis in rats: effects of chronic metabolic acidosis and potassium depletion

In order to determine intra- and inter-nephron heterogeneity of ammoniagenesis, ammoniagenic activity in microdissected nephron segments of control, acidotic and potassium (K)-depleted rats was examined. Intranephron distribution of ammoniagenic activity in control rats revealed the highest amount at the second segment of the proximal tubule (S2). Chronic metabolic acidosis induced ammoniagenesis markedly at the first segment of the proximal tubule (S1) by 235% and the thick ascending limb of Henle's loop by 198% and moderately at the S2 by 49%. K-depletion increased ammonia production significantly in the S1 by 298% and the S2 by 107%, which is a pattern quite similar to the result of chronic metabolic acidosis. Ammonia production in K-depletion was also increased in the cortical and medullary collecting tubule by 71% and 102%, respectively, probably due to increases in protein amounts (41% and 158%, respectively) there. To evaluate inter-nephron heterogeneity of ammoniagenesis, ammonia formation from glutamine in the S1 of superficial (SF) and juxtamedullary (JM) nephrons was examined. Although there was no difference in ammonia production between SF-S1 and JM-S1 in control rats, ammonia production in SF-S1 was significantly higher than that in JM-S1 in both metabolic acidosis and K-depletion. From these studies, we conclude: The increase of ammonia production in the proximal tubule was quite similar in both acidosis and K-depletion, suggesting that the main trigger of ammoniagenesis in both conditions might be a reduction of intracellular pH. SF-S1 was the nephron most reactive to acidosis and K-depletion. JM nephrons could be considered to be important not for ammonia production but for ammonia secretion.

Lithium, sodium, potassium and rubidium cation concentrations during the development of certain organs of unborn rabbits

The distribution of lithium, sodium, potassium and rubidium in rabbit fetuses was determined during the last two weeks of gestation. Samples of eye, brain, lung, heart, liver and kidney were investigated. Co-actions between the ion pairs Li+/Na+ and K+/Rb+ could be discerned. The essential properties of lithium and rubidium for the fetal development of rabbits were examined by investigating the supply of the fetal organs with these elements. Correlations between organ differentiation processes and metal concentrations were established and compared with the results obtained for the fetal development of other vertebrates.

Unusual radiological changes associated with probable Bartter's syndrome

We report 2 cases that fulfill some of the criteria for the diagnosis of Bartter's syndrome and were associated with marked radiological changes. Both patients demonstrated distortion of the caliceal pattern with medullary cavities and loss of cortical substance in the absence of vesicoureteral reflux. However, the glomerular filtration rate was well preserved. It seems unlikely that known organic renal disease was responsible for these changes and the potassium-losing state. These radiological findings also do not appear to be a consequence of hypokalemia and their pathogenesis remains uncertain.

Intracytoplasmic granules of the inner medulla and papilla of the potassium depleted human kidney

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.

Hypokalaemic hyperchloraemic metabolic acidosis and vesical stone complicating appendicovesical fistulae

Two patients with appendicovesical fistulae are described. Both presented with gastrointestinal and urinary symptoms. Biochemical examination showed hypokalaemic hyperchloraemic metabolic acidosis; radiographic investigations showed a vesical stone and a communication between the bladder and the bowel. The findings at operation suggested that the fistulae may have arisen as complications of previous appendicitis. The diagnosis of appendicovesical fistulae may be difficult but should be considered in the presence of hypokalaemic hyperchloraemic metabolic acidosis and vesical stones.

'Sick cell' hyponatraemia and gastrointestinal electrolyte loss

A patient with protracted vomiting was noted to have hyponatraemia and hypokalaemia on admission. Isotope dilution studies before treatment revealed profound body depletion of sodium, potassium and water. Treatment with potassium chloride tablets produced a simultaneous rise in serum sodium and potassium concentration without change in urine volume or osmolality, or body weight. Potassium depletion appears to have contributed to the mechanism of hyponatraemia in this situation, and that replacement of potassium corrected hyponatraemia by effectively re-distributing solute and water across the cell membrane, so that sodium ions which had entered intr-cellular fluid during electrolyte depletion, subsequently returned to extracellular fluid after treatment.

Renal manifestations of extrarenal neoplasms

In a study of 1270 consecutive autopsies there were 314 patients with malignant neoplasms arising in sites other than the kidney and central nervous system. In over 50 per cent of these there was significant renal damage related to cancer. Renal damage was produced by direct involvement of one or both kidneys by the neoplasm or by indirect effects. The latter included ischemic damage, metabolic injury, immunologic injury, and effects of therapy directed at the malignant tumor. In patients with cancer, tumor bulk and invasion of vital organs do not always explain the clinical deterioration and cause of death. Recognition of the indirect effects of tumors on the kidney and other organ systems is essential to the understanding of the generalized host response to malignant disease.

[Histopathology of the kidney in pseudo-Bartter's Syndrome induced by chronic abuse of diuretics (author's transl)]

A 38-year-old female patient developed a Pseudo-Bartter's-Syndrome with hypokalemic alkalosis, hyponatremia and hyperrenism as the result of the abuse of diuretics (furosemide, spironolactone, thiabutacide) for a period of more than 10 years. The needle biopsy specimen from the kidney showed a hyperplasia of the juxtaglomerular apparatus and of the mesangium cells as the morphologic basis of hyperrenism, a focal vacuolisation of the proximal tubular epithelium and a focal atrophy of the distal tubules. The pathogenesis of the tubular alterations and their possible relation to hypokalemia, hypoxemia or drug-toxicity is discussed, a satisfactory interpretation, however, cannot be given. The encroachment of proximal tubular epithelium on the parietal layer of Bowman's capsule is another striking pathoanatomical finding, and considered a compensatory mechanism under the continuous loss of water.

Chronic hypokalemic nephropathy: a clinical study

Description of 23 patients (21 women, 2 men) with an average age of 36.6 (19--68) years, who were hypokalemic during 6.5 years on the average (range 1/2--16 years). The cause of the potassium depletion was malnutrition (anorexia nervosa, vomiting) and/or abuse of laxatives and/or diuretics. With increasing duration of potassium depletion renal function deteriorated; in two cases terminal renal failure developed. Histology of the kidneys (9 cases) showed the picture of chronic abacterial interstitial nephritis. Urinalysis was negative or non-specific. The blood pressure levels were normal or low, hypertensive values being exceptional. Aside of hypokalemia a tendency to hyponatriemia, hypochloremia and metabolic alcalosis was observed, the latter turning into hypokalemic normochloremic acidosis with advancing renal insufficiency. Plasma renin activity and aldosterone concentration or excretion frequently were elevated, but no close correlation was found between these parameters or with the blood pressure. Bacterial infection of the urinary tract occured, if at all, in the late phase and seems to be complication rather than the cause of the kidney disease. The discussion of other possible pathogenetic factors leads to the conclusion that the term "chronic kaliopenic nephropathy" is justified. Some diagnostic and therapeutic consequences are mentioned.

Ochratoxin A and citrinin induced nephrosis in Beagle dogs. I. Clinical and clinicopathological features

Ochratoxin A and citrinin, both mycotoxins, were given separately and combined to young Beagle dogs for 14 days. Ochratoxin A, 0.1 and 0.2 mg/kg, was given by capsule, and citrinin, 5 and 10 mg/kg, was dissolved in ethanol and given by intraperitoneal injection. Clinical signs of toxicosis in dogs given 10 mg/kg citrinin and the higher combined doses included anorexia, retching, tenesmus, weight loss, prostration and death. Severity of the clinical disease and mortality were increased when the mycotoxins were combined, which indicated synergism. The clinicopathological abnormalities reflected renal damage, in that glutamic oxaloacetic transaminase and lactic dehydrogenase increased in the urine of the dogs with clinical signs of poisoning. Serum lactic dehydrogenase was increased in dogs given 10 mg/kg citrinin. Cellular and granular casts, ketones, protein and glucose were in the urine of dogs given large doses of citrinin alone or combined with ochratoxin A. Serum concentrations of sodium, potassium and chloride in the dogs given high doses of each group.

Renal changes in primary aldosteronism

The clinical presentations and renal biopsy specimens of 18 patients with primary aldosteronism were reviewed to determine the characteristic pathologic features of the kidney in this syndrome. All patients were hypertensive with a mean blood pressure of 192 nm. Hg systolic and 122 mm. Hg diastolic. The average duration of hypertension was 6.88 years. The mean serum potassium was 2.88 mEq. per l. and the mean plasma carbon dioxide was 31.4 mEq. per l. A significant history of urinary tract disease was noted in 8 patients. Laboratory and diagnostic studies evaluating renal structure and function were abnormal in 11 patients. Renal biopsies from all 18 individuals showed evidence of parenchymal damage. Hypertensive and hypokalemic changes were the most significant abnormalities and were considered moderate to severe in 78 and 89 per cent of the patients, respectively. Histologic evidence of pyelonephritis was noted in 2 patients only and no renal specimens contained characteristic changes of metabolic alkalosis. The preoperatively hypertensive and renal evaluations did not reflect the severity of the renal changes noted histologically. The extent of renal injury caused by hypertension and hypokalemia in these patients emphasizes the consequences of primary aldosteronism. Early diagnosis and treatment of this disorder are essential if these consequences are to be avoided.

Effects of colchicine and vinblastine on the cellular action of vasopressin in mammalian kidney. A possible role of microtubules

To evaluate the possible role of microtubules in the cellular action of vasopressin on the mammalian kidney, the effects of microtubule-disrupting agents were studied in vivo and in vitro. In vivo studies were done in rats in mild to moderate water diuresis induced by drinking 5% glucose. Microtubule-disrupting alkaloids, colchicine (0.1 mg/day) or vinblastine (0.08 mg/day), given intraperitoneally, did not change water and solute excretion itself, but blocked or markedly inhibited the antidiuretic response (increase in urine osmolality and decrease in urine flow) to exogenous vasopressin. Total solute excretion was unaffected by these two alkaloids and there were no substantial changes in excretion of sodium, potassium, or creatinine. Lumicolchicine, a derivative of colchicine that does not interact with microtubules, did not alter the antidiuretic response to exogenous vasopressin. Activities of adenylate cyclase in the renal medullary plasma membrane, and cyclic AMP phosphodiesterase and protein kinase in renal medullary cytosol, were not influenced by 10(-5)-10(-4) M colchicine or vinblastine in vitro. Studies on the subcellular distribution of microtubular protein (assessed as [(3)H]colchicine-binding protein) in renal medulla shows that this protein is contained predominantly in the cytosol. Particulate fractions, including plasma membrane, contain only a minute amount (less than 6%) of the colchicine-binding activity. The results suggest that the integrity of cytoplasmic microtubules in cells of the distal nephron is required for the antidiuretic action of vasopressin, probably in the sites distal to cyclic AMP generation in the mammalian kidney.

Ochratoxicosis in Beagle dogs. I. Clinical and clinicopathological features

Rice culture of Aspergillus ochraceus that contained ochratoxin A or pure crystalline ochratoxin A was administered orally daily to 23 young male Beagle dogs. Six other young male Beagles served as controls. Most dogs were killed in extremis on or before day 14 after receiving a daily oral dose of ochratoxin A, 0.2–3.0 mg/kg body weight. Consistent clinical features of the mycotoxicosis were anorexia, weight loss, emesis, tenesmus, passage of clots of blood-stained mucus from the rectum, rectal temperature up to 107°F, tonsillitis, dehydration and prostration. The prominent clinicopathological features of the toxicosis were a reflection of renal damage. The urine had a specific gravity as low as 1.004 and contained granular casts, necrotic renal epithelium, and concentrations above normal of protein, glucose, lactic dehydrogenase, isocitric dehydrogenase, leucine aminopeptidase, glutamic-pyruvic transaminase, glutamic-oxalacetic transaminase, and alkaline phosphatase. Serum concentrations of these enzymes did not change. Concentrations of blood urea nitrogen remained, with two exceptions, within the normal range, but the concentrations of blood glucose declined terminally. Serum concentrations of the liver-specific enzyme, γ-glutamyl transpeptidase and sulfabromophthalein dye retention time did not indicate hepatic dysfunction.