A rare case of congenital distal renal tubular acidosis combined with medullary sponge kidney

Hypokalemic Periodic Paralysis Secondary to Medullary Sponge Kidney Complicated With Renal Tubular Acidosis

Hypokalemic periodic paralysis has a high risk of life-threatening dysrhythmias. Hyperchloremic acidosis with hypokalemia is a dangerous condition. There are several causes of hypokalemia, in addition to common diseases, such as hyperthyroidism, hyperaldosteronism, and Cushing’s syndrome; the other rare diseases include renal tubular acidosis (RTA), Bartter’s syndrome, and Gitelman’s syndrome. We present an unusual case of hypokalemic periodic paralysis, which was caused by a medullary sponge kidney with distal RTA. The patient had no significant medical history and was not taking any conventional drugs. Investigations demonstrated a combination of hypokalemia, hyperchloremia, metabolic acidosis with a normal anion gap, relatively raised urinary pH, and decreased phosphate level. Results suggested a diagnosis of RTA with secondary hyperparathyroidism. After potassium citrate replacement and correction of acidosis, the patient’s condition was in remission. This case highlights the rare etiology of hypokalemia and the need to actively search for the pathogenesis of unexplained hypokalemia to avoid delaying the condition.

Nephrocalcinosis in adolescent girl with medullary sponge kidney and mild hemihypertrophy: A case report

RATIONALE

Medullary sponge kidney (MSK) is a rare congenital abnormality characterized by cystic dilatation of the medullary collecting tubules. The disorder is likely to be complicated by nephrocalcinosis, urolithiasis, tubular dysfunctions, and urinary tract infections. In addition, it may be rarely associated with extrarenal anomalies.

PATIENT CONCERN

We present a case of 17-year old girl who was referred for metabolic evaluation of bilateral nephrocalcinosis. Physical examination showed signs of mild, left-sided hemihypertrophy involving the lower limb, buttock, trunk, face, and tongue. The imaging studies of kidneys including intravenous urography and contrast computed tomography showed numerous medullary calcification and a typical picture of MSK-"paint brush"/"bouquet of flowers" appearance of the dilated tubules within the renal medulla. Laboratory evaluation revealed sterile pyuria, hypercalciuria, and hypocitraturia.

INTERVENTION

The patient was subsequently treated with potassium citrate, hydrochlorothiazide, low sodium and low oxalate diet accompanied by high fluid intake.

OUTCOMES

After a 1-year therapy the normalization of calciuria and citraturia occurred and no progression of nephrocalcinosis was observed.

LESSONS

We conclude that MSK should always be considered as a cause of nephrocalcinosis. Since the final diagnosis requires specific imaging techniques, the concomitant extrarenal abnormalities such as hemihypertrophy may facilitate diagnostic decisions.