Rhabdomyolysis and myoglobinuria. Association with hypokalemia of renal tubular acidosis

Long-term complications of primary distal renal tubular acidosis

The clinical manifestations of primary distal renal tubular acidosis usually begin in childhood, but the disease is caused by a genetic defect that persists throughout life. This review focuses on the complications of distal tubular acidosis that occur or remain long-term such as nephrocalcinosis and urolithiasis, growth impairment, bone mineralization, severe hypokalemia, kidney cysts, and progressive kidney failure, as well as other persistent manifestations that occur independent of acidosis but are associated with some inherited forms of the disease. The pathogenic factors responsible for kidney failure are discussed in particular because it is a complication to which different publications have recently drawn attention and which affects a high percentage of adults with primary distal renal tubular acidosis. The need to maintain optimal metabolic control of the disease and scheduled clinical follow-up throughout life and the importance of organizing protocols for the transition of patients to adult nephrology services are emphasized.

[Celiac crisis with quadriplegia due to potassium depletion as presenting feature of celiac disease]

INTRODUCTION

Adult coeliac disease revealed by coeliac crisis and quadriplegia due to potassium depletion is an extremely rare situation.

CASE REPORT

A 26-year-old woman presented with a suddenly developed weakness of all four limbs and a severe diarrhea. Authors emphasize coeliac crisis, which is a presenting feature of coeliac disease, characterized by acute diarrhea with life-threatening acid base and electrolyte abnormalities. The patient improved with correction of hypokalemia and gluten-free diet.

CONCLUSION

A severe acute diarrhea with metabolic and systemic complications, the so-called coeliac crisis, is a possible presenting clinical feature of a previously undiagnosed adult celiac disease.

Effects of (-)-epigallocatechin gallate on the redox reactions of human hemoglobin

The toxicity of acellular hemoglobin (Hb)-based therapeutics has been attributed in part to the uncontrolled oxidative reactions. A variety of antioxidant strategies to ameliorate potential oxidative damage in vivo have been suggested. We have examined the effects of (-)-epigallocatechin gallate (EGCG), a green tea polyphenol compound widely regarded as a chain-breaking antioxidant, on the oxidative stability of diaspirin crosslinked Hb (DBBF) and its cytotoxic ferryl intermediate. DBBF (ferrous) was rapidly oxidized to the ferric form in the presence of EGCG relative to the normal spontaneous oxidation of this Hb. The fast elimination of ferrous Hb is probably due to the ability of EGCG to produce hydrogen peroxide (H2O2) as these reactions were almost completely reversed by the addition of catalase and superoxide dismutase to the reaction medium. EGCG, however, effectively reduced ferryl back to ferric Hb in a biphasic kinetic reaction at physiological pH. At acidic pH where the autoreduction of protonated ferryl Hb is enhanced, a monophasic reduction process of the ferryl heme is achieved. A balance between pro and antioxidant properties of EGCG should be taken into account if EGCG is used in combination therapy with redox active acellular Hbs.

Atypical presentation of distal renal tubular acidosis in two siblings

Primary distal renal tubular acidosis (dRTA) is an inherited disease characterized by the inability of the distal tubule to lower urine pH <5.50 during systemic acidosis. We report two male siblings who presented with severe hyperchloremic metabolic acidosis, high urinary pH, nephrocalcinosis, growth retardation, sensorineural hearing loss, and hypokalemic paralysis. Laboratory investigations revealed proximal tubular dysfunction (low molecular weight proteinuria, generalized hyperaminoaciduria, hypophosphatemia with hyperphosphaturia, and hypouricemia with hyperuricosuria). There was significant hyperoxaluria and laboratory evidence for mild rhabdomyolysis. Under potassium and alkali therapy, proximal tubular abnormalities, muscular enzymes, and oxaluria normalized. A homozygous mutation in the ATP6V1B1 gene, which is responsible for dRTA with early hearing loss, was detected in both siblings. In conclusion, proximal tubular dysfunction and hyperoxaluria may be found in children with dRTA and are reversible under appropriate therapy.

Iron chelators can protect against oxidative stress through ferryl heme reduction

Iron chelators such as desferrioxamine have been shown to ameliorate oxidative damage in vivo. The mechanism of this therapeutic action under non-iron-overload conditions is, however, complex, as desferrioxamine has properties that can impact on oxidative damage independent of its capacity to act as an iron chelator. Desferrioxamine can act as a reducing agent to remove cytotoxic ferryl myoglobin and hemoglobin and has recently been shown to prevent the formation of a highly cytotoxic heme-to-protein cross-linked derivative of myoglobin. In this study we have examined the effects of a wide range of iron chelators, including the clinically used hydroxypyridinone CP20 (deferriprone), on the stability of ferryl myoglobin and on the formation of heme-to-protein cross-linking. We show that all hydroxypyridinones, as well as many other iron chelators, are efficient reducing agents of ferryl myoglobin. These compounds are also effective at preventing the formation of cytotoxic derivatives of myoglobin such as heme-to-protein cross-linking. These results show that the use of iron chelators in vivo may ameliorate oxidative damage under conditions of non-iron overload by at least two mechanisms. The antioxidant effects of chelators in vivo cannot, therefore, be attributed solely to iron chelation.

Hypokalemic rhabdomyolysis without watery diarrhea: an unexpected presentation of a pancreatic neuro-endocrine tumor

Pancreatic polypeptide (PP) islet cell tumors are usually not associated with a distinct clinical syndrome, although some reports suggest that they can cause a watery diarrhea syndrome similar to vasoactive intestinal polypeptide (VIP) cell tumors. We report the case of a young woman with an unusual presentation of a pancreatic neuroendocrine tumor mainly secreting PP. The patient developed a reversible hypokalemic rhabdomyolysis very likely secondary to the presence of the tumor. The myopathy resolved following the restoration of normokaliemia using potassium supplementation and a partial laparoscopic pancreasectomy. Isolated cases of hypokalemic rhabdomyolysis induced by intestinal diseases have been described in literature but these did not include gastroenteropancreatic neoplasms. We suggest that pancreatic neuroendocrine tumors should be added to the list of intestinal diseases capable of producing hypokalemic myopathy.

Hypokalemia causing rhabdomyolysis resulting in life-threatening hyperkalemia

Hyperkalemia is commonly associated with renal failure and is rare if renal function is normal. It is rarely caused by rhabdomyolysis and can be life threatening if unrecognized. Rhabdomyolysis is caused by many disorders, including hypokalemia. The available literature, both for human beings and experimental animals, contains evidence of hypokalemia causing rhabdomyolysis and rhabdomyolysis leading to hyperkalemia. Hypokalemia as a cause of rhabdomyolysis often goes unnoticed, because of the counteracting effect of rhabdomyolysis on serum potassium. There are no pediatric reports showing hypokalemia as a cause of rhabdomyolysis leading to life-threatening hyperkalemia. This case emphasizes the vigilance required toward the occurrence of rhabdomyolysis, which if not detected promptly may prove fatal.

Myoglobinuria

Myoglobinuria refers to an abnormal pathologic state in which an excessive amount of myoglobin is found in the urine, imparting a cola-like hue, usually in association with myonecrosis and a clinical picture of weakness, myalgias, and edema. Myoglobinuria is produced by multiple causes: any condition that accelerates the use or interferes with the availability of oxygen or energy substrates to muscle cells can result in myoglobinuria, as can events that produce direct muscle injury, either mechanical or chemical. Acute renal failure is the most serious complication, which can be prevented by prompt, aggressive treatment. In patients surviving acute attacks, recovery of muscle and renal function is usually complete.

Myoglobinuria, malignant hyperthermia, neuroleptic malignant syndrome and serotonin syndrome

This article presents an overview of the causes and manifestations of myoglobinuria and provides criteria for its diagnosis and management. The article also reviews neuroleptic malignant syndrome, malignant hyperthermia, and serotonin syndrome, all of which could cause rhabdomyolysis and myoglobinuria.

Experimental potassium depletion myopathy

Myopathic morphological changes were observed in the calf muscles of rats maintained on a potassium-depleted diet for 30-50 days. Light-microscopic changes were more severe in the superficial gastrocnemius muscle fibres and included pallor, swelling and vacuolation, progressing to necrosis, mononuclear cell infiltration and phagocytosis. Mitochondrial disruption, transverse tubular dilatation, membranous body formation and vacuolation were seen on ultrastructural examination. Both vacuoles and subsarcolemmal membranous bodies were shown to be in continuity with the transverse tubular system. More advanced myopathic changes were those of sarcomere destruction and muscle fibre necrosis. Morphological changes resemble those of human potassium depletion myopathy. Ineffective energy metabolism and focal ischaemia due to impaired vasodilatation are proposed as mechanisms for the myopathy of potassium depletion.

Skeletal muscle resting membrane potential in potassium deficiency

The resting transmembrane potential of skeletal muscle (E(m)) is thought to be a function of the ratio of intracellular to extracellular potassium concentration ([K(i)]/[K(o)]). In potassium deficiency, the fall of [K(i)] is proportionately less than the fall of [K(o)], thus theoretically predicting a rise of E(m). To examine this theory and to characterize E(m) in kaliopenic myopathy, muscle composition and E(m) were measured during moderate (n = 5) and severe (n = 11) K deficiency in the dog and compared with measurements in the severely K-deficient rat (n = 10). Mean measured E(m) rose during moderate K deficiency in four of five dogs (-85.4 to -94.6 mV) and during severe K deficiency in the rat (-89.1 to -94.9 mV). Both values closely approximated the increase in E(m) predicted by the Goldman equation. In contrast, during severe K deficiency in the dog, a significant decline (P < 0.001) of mean E(m) to -55 mV was observed.Since skeletal myopathy and paralysis do not occur in the rat as a consequence of K deficiency, the observation that E(m) falls as paralysis occurs in the unexercised dog suggests that alteration of muscle membrane function may play a role in kaliopenic myopathy. Such an event could explain the ease with which frank muscle necrosis may be induced by exercise in the K-deficient dog.