[Significance of the urine strip test in case of stunted growth]

Abstract

Observation of stunted growth in children usually leads the general practitioner to refer the patient to endocrinologists or gastroenterologists. In most cases, after a complementary check-up, the diagnosis is made and treatment is initiated. However, certain cases remain undiagnosed, particularly renal etiologies, such as proximal tubulopathy. The urine strip test at the initial check-up would be an easy and inexpensive test to avoid delayed diagnosis. The aim of the present paper is to increase general physicians' and pediatricians' awareness of the significance of questioning the parents and using the urine strip test for any child presenting stunted growth. We report a patient case of a 20-month-old child admitted to the emergency department for severe dehydration. He had displayed stunted growth since the age of 5 months and showed a negative etiologic check-up at 9 months of age. Clinical examination at admission confirmed stunted growth with loss of 2 standard deviations and signs of dehydration with persistent diuresis. Skin paleness, ash-blond hair, and signs of rickets were also observed and the urine strip test showed positive pads for glycosuria and proteinuria. Polyuria and polydipsia were also revealed following parents' questioning, suggesting proximal tubulopathy (Fanconi syndrome). Association of stunted growth, rickets, polyuria and polydipsia, glycosuria (without ketonuria and normal glycemia), and proteinuria suggest nephropathic cystinosis. Ophthalmic examination showed cystine deposits in the cornea. The semiotic diagnosis of nephropathic cystinosis was confirmed by leukocyte cystine concentrations and genetic investigations. This case report clearly illustrates the significance of the urine strip test to easily and quickly concentrate the diagnosis of stunted growth on a renal etiology (glycosuria, proteinuria), especially on proximal tubulopathy for which the most frequent cause is nephropathic cystinosis. Specificity of nephropathic cystinosis treatment is that the age of treatment initiation is crucial and determinant for the prognosis of the disease and the onset of final stage renal failure. Therefore, the urine strip test should be included in the systematic check-up of stunted growth to identify any renal etiology.