Cystinosis is a multisystem disorder with varied presentations secondary to deposition of cystine crystals in different organ systems. Children with cystinosis typically present with renal tubular acidosis and failure to thrive. We report a 3-year-old girl, born to a third-degree consanguineous couple, who presented with failure to thrive and polyuria. Laboratory investigations showed metabolic alkalosis suggestive of a Bartter-like syndrome and acquired hypothyroidism. Although metabolic alkalosis is a rare manifestation of cystinosis, the presence of renal tubular dysfunction and hypothyroidism prompted consideration of a probable diagnosis of cystinosis in the index child. Slit-lamp examination revealed cystine crystals in the cornea and genetic analysis showed a mutation in exon 9 of the CTNS (cystinosin, lysosomal cystine transporter) gene on chromosome 17. We highlight the importance of considering cystinosis as a differential diagnosis for Bartter syndrome and hypothyroidism.
- metabolic disorders
- thyroid disease
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Contributors RK and GD were involved in the conception of the work, acquisition, analysis and interpretation of data and drafting the work. RK, GD and AK were involved in clinical management of the case. PMN and AK were involved in drafting the manuscript and revising it critically for important intellectual content. All authors have read the manuscript and approved it for final submission. All authors have agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer-reviewed.
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