![Diagnosing cystinosis](/media/tk4blspr/lens.png?anchor=center&mode=crop&width=150&rnd=132925283335200000)
Diagnosing cystinosis
Diagnosis
Diagnosis of nephropathic cystinosis should be made as soon as possible, to facilitate prompt initiation of treatment and prevention of long-term complications.1
A diagnosis of cystinosis is usually made on the basis of patient presentation and the results of laboratory investigations, as summarised below.2
Investigations to support a diagnosis of cystinosis
![WBC cystine assay](/media/ehmpitxf/sample.png)
White blood cell (WBC) cystine assay3
• The most common means to confirm diagnosis
• Cystine concentration is measured in preparations of mixed leukocytes or polymorphonuclear leukocytes
![Slit-lamp examination](/media/nk2fp5d5/eye.png)
Slit-lamp examination2
Corneal cystine crystals are usually visible on a slit-lamp examination, and may be the initial diagnosing criterion for late-onset patients
![Patient history and clinical symptoms](/media/2l1ma4wf/note.png)
Patient history and clinical symptoms1,2,4
• Failure to thrive
• Polyuria, polydipsia, vomiting, constipation
• Rickets
• Lighter skin and hair colour (a classic but not universal finding)
![Laboratory tests](/media/imppn1lc/drops.png)
Laboratory tests1,4
• Serum electrolytes, protein, minerals, glucose
• Urinalysis to confirm and quantify renal glucose, protein, electrolyte, and mineral wasting
![Other procedures](/media/v0vf5wsb/samples.png)
Other procedures2,4
• Imaging may help assess complications associated with cystinosis
• Renal or other tissue biopsy (rare)
• Genetic testing, while not required for diagnosis, may be useful to confirm diagnosis prior to treatment initiation and to characterise specific mutations
Explore the sections below to find out more.
![Kidneys](/media/f2fhk2i4/kidneys.png?anchor=center&mode=crop&width=150&height=150&rnd=132925283336600000)
![People](/media/04phwtbl/people.png?anchor=center&mode=crop&width=150&height=150&rnd=132925283333200000)
![Lens](/media/tk4blspr/lens.png?anchor=center&mode=crop&width=150&height=150&rnd=132925283335200000)
Diagnosing cystinosis
Investigations required to support a diagnosis of cystinosis
![Pill](/media/ebafzotx/pill.png?anchor=center&mode=crop&width=150&height=150&rnd=132925283339600000)
![Notes](/media/bxubtdsk/notes.png?anchor=center&mode=crop&width=150&height=150&rnd=132925283338170000)
![Tools](/media/kcwp1mng/tools.png?anchor=center&mode=crop&width=150&height=150&rnd=132925283340770000)