Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Biotinidase is measured in plasma for the diagnosis of biotinidase deficiency, a rare autosomal recessive disorder of biotin recycling and utilisation of dietary protein-bound biotin.
Clinical features of the disorder include lethargy, muscular hypotonia, seizures and ataxia. Patients may also have developmental delay, hearing loss, conjunctivitis, visual problems and skin rash. Symptoms may develop gradually with periods of remission and are usually reversed on treatment with biotin.
Biotinidase deficiency may be suspected following identification of secondary abnormalities on urine organic acids and blood spot acylcarnitines.
Treatment with biotin does not affect the result of plasma biotinidase analysis.
Specimen container paediatric:
Lithium heparin plasma or EDTA plasma
Specimen container adult:
Lithium heparin plasma or EDTA plasma
Minimum volume paediatric:
250 uL blood
Minimum volume adult:
2 mL blood
Transport requirements:
Ward: send the sample at ambient temperature. Sample should be separated on receipt and plasma frozen.
External hospitals: send plasma frozen
Interpretation:
Biotinidase activity below the reference range may be due to sample degradation if the storage and transport requirements are not followed.
Very low plasma biotinidase (< 0.4 nmol/ml/min) indicates profound biotinidase deficiency.
Borderline results may be due to partial biotinidase deficiency.
Abnormal results should be confirmed on a repeat sample; urine organic acids and blood spot acylcarnitines may be helpful in interpreting results.
Reference ranges:
1.9 – 5.1 nmol/ml/min