Cystinosis: the importance of early diagnosis

ABSTRACT

Cystinosis is a leading cause of Fanconi syndrome in childhood. We report a 7-year-old Pakistani boy who presented at the age of 5 months with vomiting, failure to thrive and rickets. At the age of 15 months he had typical biochemical findings of Fanconi syndrome and was prescribed electrolyte supplements. At the age of 6 years he presented to us with photophobia and renal failure in addition to the previous complaints, and was found to have hazy corneas. Cystinosis was suspected and confirmed by finding typical corneal and bone marrow cystine crystals. Leukocyte cystine was 7.3 nmol 0.5 cystine/mg protein [normal < 0.2]. The patient was started on L-thyroxine, 1 -alpha-cholecalciferol, in addition to electrolyte supplements and it was planned to start him on phosphocysteamine and to proceed to renal transplant. However, his renal failure was rapidly progressive. At the age of 7 years, after taking phosphocysteamine for 10 days, he was admitted with epistaxis and haematemesis; he required haemodialysis, bled massively into his chest after central line insertion and died within 2 months after suffering from severe hypoxic brain damage. We conclude although Cystinosis is a leading cause of Fanconi syndrome in North America, it is quite rare in Saudi Arabia. Second, Cystinosis is a generalized disease, and the involvement of the blood vessels might have led to the intrathoracic bleeding in our patient. Third, the importance of early diagnosis and treatment is stressed