8.2 Diagnosis

Children are considered to be high-risk patients and need a full metabolic work up. The patient's history is particularly important as many metabolic disorders are hereditary [e.g. autosomal recessive disorders (cystinuria, primary hyperoxaluria, 2,8-dihydroxyadenine and xanthine calculi); autosomal dominant disorders (renal tubular acidosis, idiopathic hypercalciuria)]. In cases of a positive family history, an unfavourable clinical course has to be reckoned with.

In children, hypercalciuria with hypercalcaemia is frequently caused by immobilization (e.g. during fracture treatment). Another rare condition is hyperparathyroidism. As stone formation only occurs in a subset of immobilized children, a complete metabolic work up should be performed, as other metabolic disorders may facilitate the manifestation.

It must also be emphasized that the normal values of the excretion rate of lithogenous and inhibitory agents in adults cannot be applied to children, but requires correction for body weight (mmol/kg/d) as below. Variation between laboratories must also be considered.

Table 12: Critical values for renal excretion in children: when to start therapy

Tlease note the presence of citrate splitting bacteria in the urine sample