Clinical use
Diagnosis & monitoring of congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Identification of heterozygotes for congenital adrenal hyperplasia and diagnosis of mild congenital adrenal hyperplasia (also referred to as late-onset and cryptic forms).
Background
17a-Hydroxyprogesterone is an intermediate in the biosynthesis of cortisol. Deficiency of either 11b- or 21-hydroxylase activities leads to an increased concentration of 17a-hydroxyprogesterone in the peripheral circulation. This test is less valuable in 11b-hydroxylase deficiency, where 11-deoxycortisol is the analyte of choice. ‘Functional’ deficiencies of 21-hydroxylase and 11b-hydroxylase have been described.
Reference ranges
- Infants less than 1 year
- <9 nmol/L
- Adult Males
- 1.9 – 6.5 nmol/L
- Adult Females
- Follicular Phase: 1.0 – 4.5 nmol/L
- Luteal Phase: 0.8 – 8.8 nmol/L
Warning
Do not take 17OHP sample until at least 5 days after birth for full term baby
17a-hydroxyprogesterone false positive results may occur in premature babies when the sample is taken soon after birth and also in ill babies.
For treatment levels – clinician may be looking for pre-dose level (how out of control?) or 2 hour post-dose (how effective is treatment?).
Hydrocortisone treatment should lead to feedback suppression of ACTH and drop in 17-OHP levels.
Patient preparation
Diagnosis of congenital adrenal hyperplasia
Take blood into an SST tube before any emergency administration of corticosteroids and preferably in the early morning. All new cases should be confirmed by urine steroid profiling.
Monitoring response to treatment
Take blood (1mL) between 8am and 9am before initiation of treatment for the day and again 2 hours after the first dose of corticosteroid. Further samples may be taken through the day. Record the time of any therapy given. Adequacy of treatment may be better judged if combined with the measurement of androstenedione.
Specimen requirements
A serum samples (SST) is required for analysis, blood spot Guthrie cards are also acceptable.
Turnaround time
1 week
Analysing Laboratory
Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP