Cystinosis is a lysosomal storage disease with accumulation of cystine within lysosomes. In untreated children a major problem is renal involvement.
Patient selection: cystinosis
Pathogenesis: accumulation of cystine in cells
Onset: usually during infancy
Clinical features:
(1) renal Fanconi syndrome with polyuria, polydipsia, and dehydration
(2) hypophosphatemic/calcipenic rickets
(3) poor growth with failure to thrive and short stature
(4) deteriorating glomerular filtration
(5) feeding difficulties
(6) tetany
Laboratory findings:
(1) hypochloremic acidosis
(2) increased renal wastage of sodium, potassium, bicarbonate, calcium, phosphate and magnesium
(3) elevated serum alkaline phosphatase
(4) hypokalemia
(5) hypocalcemia
(6) hypophosphatemia
(7) deterioration in eGFR
Imaging findings:
(1) osteopenia with rickets
(2) medullary nephrocalcinosis
