The dihydrotestosterone assay for identifying 5α-reductase deficiency: a five-year audit from a UK tertiary Paediatric Centre
Iain Martin1, Natalie Smee2, Jane Mcneilly1, Martina Rodie2 & Faisal Ahmed2
Background: The DHT RIA is often used in the assessment of children with suspected DSD. Affected cases have a history of consanguinity in ≤50% and many may not have a non-Caucasian background (Maimoun et al., JCEM, 2011). We aimed to assess the clinical utility of the DHT RIA in identifying cases of 5-ARD.
Methods: All DHT requests in a 5 year period in a major UK tertiary paediatric centre were identified and case notes were retrieved and searched to identify the clinical background of each patient, DHT results, rationale for testing and other biochemical investigations performed.
Results: 141 tests were performed on 74 patients over 5 years. In 58/74 (78%) patients case notes were available and included 6 (10%) girls and 52 (90%) boys. The median EMS score of these children at birth was 9 (range 012). Of the case notes examined all but one patient had DHT levels requested by an endocrinologist. Median age at test was 2 years, (range 1 week18 years) and median DHT result was 0.37 nmol (range <0.12.72 nmol). Twenty-eight patients (48%) had the test as part of 3 days hCG stimulation test, 12 (20%) patients had the test during a prolonged hCG stimulation test, 13 patients (22%) were tested during a routine endocrine screen and 4 (7%) patients were tested for other reasons. In 5 (9%) cases samples were missing at D4 or D22. The median T; DHT ratio at baseline, D4 and D22 was 7 (2.494), 13.1 (3.840) and 10.6 (5.149.3) respectively. Two boys with 5-ARD were identified after testing. These two were brothers of South Asian origin with a history of consanguinity and who had micropenis. The T: DHT ratio in these two cases was 5, 44 and 7, 27 before and after hCG stimulation.
Discussion: Our results question the routine use of the DHT RIA in all boys with XY DSD. The reliability of this test needs to be compared to liquid chromatography-tandem mass spectrometry and genetic testing for SRD5A2.