Cystine, ornithine, lysine and arginine, urine
Clinical Background:
Cystinuria is an inherited disorder characterized by the impaired reabsorption of cystine in the proximal tubule of the nephron and the gastrointestinal epithelium. The only clinically significant ...
Cystinuria is an inherited disorder characterized by the impaired reabsorption of cystine in the proximal tubule of the nephron and the gastrointestinal epithelium. The only clinically significant manifestation is recurrent nephrolithiasis secondary to the poor solubility of cystine in urine. Although cystinuria is a relatively common disorder, it accounts for no more than 1% of all urinary tract stones. Thus far, mutations in 2 genes, SLC3A1 and SLC7A9, have been identified as being responsible for most cases of cystinuria by encoding defective subunits of the cystine transporter. With the discovery of mutated genes, the classification of patients with cystinuria has been changed from one based on phenotypes (I, II, III) to one based on the affected genes (I and non-type I; or A and B). Most often this classification can be used without gene sequencing by determining whether the affected individual's parents have abnormal urinary cystine excretion. Clinically, insoluble cystine precipitates into hexagonal crystals that can coalesce into larger, recurrent calculi. Prevention of stone formation is the primary goal of management and includes hydration, dietary restriction of salt and animal protein, urinary alkalinization, and cystine-binding thiol drugs.
Test Details
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Discipline:
Biochemistry
Biochemistry
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Minimum Volume Adult:
1 mL urine
1 mL urine
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Minimum Volume Paediatric:
1 mL urine
1 mL urine
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Reference Ranges:
24h urine (µmol/24h)
up to 4w
0 - 43
1m - 12m
0 - 52
1 - 4y
0 - 24
5 - 11y
0 - 51
12 - 17y
0 - 119
Adult
0 - 186
Random urine (µmol/mmol)
...Read More24h urine (µmol/24h)
up to 4w
0 - 43
1m - 12m
0 - 52
1 - 4y
0 - 24
5 - 11y
0 - 51
12 - 17y
0 - 119
Adult
0 - 186
Random urine (µmol/mmol)
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Routine Contact Name:
Duty biochemist
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Routine Telephone:
Freeman: 0191 244 8889
RVI: 0191 282 9719
Freeman: 0191 244 8889
RVI: 0191 282 9719
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Routine Email:
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Specialist Test:
Yes
Yes
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Specialist Contact Name:
Metabolic Clinical Scientist
Metabolic Clinical Scientist
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Specialist Telephone:
0191 282 9685 (Consultant Clinical Scientist)
0191 282 0334 (Metabolic Laboratory)
0191 282 9685 (Consultant Clinical Scientist)
0191 282 0334 (Metabolic Laboratory)
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Specialist Email: