Idiopathic Hypercalciuria in Children

Idiopathic Hypercalciuria (IH), a heterogenous disorder, is the most common cause of urolithiasis in children. IH patients present frequently with gross or microscopic hematuria, abdominal pain and a variety of urinary tract complaints (frequency-dysuria syndrome, enuresis, recurrent tract infection), with-noncalculus manifestation more prevalent than stone disease. Recently, osteopenia has been found in a high percentage of IH children even at the time of diagnosis. IH is characterized by urinary calcium excretion greater than 4mg/kg/day with normocalcemia in the absence of any other causes of hypercalciuria such as vitamin D intoxication, primary hyperparathyroidism, hyperthyroidism, immobilization, endogenous or exogenous glucocorticoid excess, distal renal tubular acidosis and furesemide medication. This complex metabolic disease is considered to be of genetic origin, as in some cases, it seems to be inherited in an autosomal dominant pattern. A variety of genes participating in the mechanisms of Ca homeostasis, have attracted the interest of researchers in order to elucidate the pathogenetic mechanism of the disease and thus determining the appropriate treatment for any distinct patient. However, no specific gene or polymorphisms are yet identified. Furthermore, studies on the pathophysiology of IH distinguish two prominent types of IH: the absorptive, characterized by increased intestinal Ca absorption, and the renal, characterized by decreased tubular Ca reabsorption. The distinction between renal and absorptive type could direct towards the better therapeutic protocol. Generally, the main goal of treatment applied on hypercalciuric children should be to alleviate and finally eliminate the symptoms of the disease, to prevent renal stone formation or recurrence and to permit the acquisition of the optimal bone mass. Initial management of those patients consists primarily of high fluid intake and dietary salt restriction. If the symptoms persist, thiazide diuretics prescription is ideal, especially for IH patients of renal type. Keywords: Urolithiasis, hematuria, hyperparathyroidism, Osseous Resorption, CLCN5 mutations