An indirect enzyme immunoassay for the measurement of total 17alpha-hydroxyprogesterone (17OHP) in serum using monoclonal antibodies generated in our laboratory was developed. Here, (a) instead of extraction with solvents, serum was heated to free protein-bound 17OHP and assay was performed at pH 9.6, (b) to ensure uniform assay conditions for both standards and samples, buffer for standards contained charcoal-stripped pre-heated pooled cord serum. Assays were done in 96-well EIA microplates pre-coated with 17alpha-hydroxyprogesterone-3-(o-carboxymethyl)oxime: bovine serum albumin. Secondary antibody was horseradish peroxidase-linked sheep anti-mouse IgG polyclonal antibody. The method was accurate and suitable for screening for congenital adrenal hyperplasia.
Congenital Adrenal Hyperplasia (CAH) is primarily caused by mutations in genes responsible to produce enzymes involved in the synthesis of cortisol, aldosterone, or both. This study aims to determine the prevalence, sociodemographic distributions, and clinical factors associated with CAH in the Malaysian population. This retrospective study reviewed laboratory records of 17-hydroxyprogesterone (17OHP) test requests received at the Institute for Medical Research, Kuala Lumpur from January 2021 to December 2021. Descriptive statistics were employed for most variables, and logistic regression analysis was conducted to determine factors associated with CAH. The dataset included a total of 775 patients (64.2%) from 1,207 test requests screened. The prevalence of newly diagnosed CAH in the year 2021 was 13.5% (n=105). The majority were Malays (15.1%), neonates (13.8%), and females (45.7%). Higher baseline 17-OHP (cOR:1.31, 95% CI:1.19, 1.45), unknown gender at birth (cOR:7.82, 95% CI:2.86, 21.37), and neonatal age group at presentation (cOR:29.3, 95% CI:12.07, 71.03) independently predict CAH. The high prevalence of CAH in our region has been speculated to be due to the cultural consanguinity norms, resulting in genetic aberrations. CAH may manifest as ambiguous genitalia, particularly in females, due to the overproduction of androgens in-utero, resulting in atypical genitalia, necessitating thorough investigation. To the best of our knowledge, the data presented are the latest report on CAH prevalence, distribution, and description of positive CAH cases in the Malaysian population. These findings are essential for further public health planning to improve the diagnostic capacity and clinical management of CAH.
Since conventional radioimmunoassays (RIA) for measurement of 17-hydroxyprogesterone (17-OHP) in serum samples require a laborious solvent extraction step, a direct and rapid in-house RIA was developed for early diagnosis and management of congenital adrenal hyperplasia (CAH). In-house rabbit anti-17-OHP antiserum, tritium labelled 17-OHP and dextran-coated charcoal were used in assay buffer with low pH 5.1 and preheated serum samples. Both inter- and intra-assay CVs were < 10% and the sensitivity was 1.2 nmol/l or 12 fmol/tube. Results from the direct assay correlated well with values from an extraction assay, r = 0.88 in samples from CAH patients, r = 0.85 in adults and children, 0.69 and 0.40 in term and preterm neonates respectively, 0.66 and 0.63 in luteal phase and third trimester pregnancy; p < 0.001 in all groups except p < 0.05 in preterm neonates. However, results from the direct assay were two to three times higher in serum samples from CAH patients, normal adults and children, but were five to seven times higher in pregnancy and term neonates and thirty times higher in preterm neonates. The markedly elevated levels measured by the direct assay are probably due to cross-reactivities with water-soluble steroid metabolites such as 17-hydroxypregnenolone sulphate and dehydroepiandrosterone sulphate (DHEAS). Although the direct assay is only useful as a screening test for preterm babies, it can be used for both diagnosis and monitoring of treatment of CAH in all other age groups.
An in-house radioimmunoassay (RIA) for the measurement of androstenedione levels in serum was established and validated. Levels of androstenedione were measured by RIA using serum samples from various normal population groups and patients with congenital adrenal hyperplasia (CAH). Analytical recovery and linearity results were > 95%, while intra- and inter-assay CVs were < 10% and < 22% respectively. The assay sensitivity was 0.5 nmol/l or 25 fmol/tube. In normal population groups, the highest androstenedione levels were found in preterm neonates (1.6-12.4 nmol/l), followed by adult females (1.5-10.2 nmol/l), adult males (1.6-8.0 nmol/l) and term neonates (0.8-8.8 nmol/l), while the lowest values were observed in prepubertal children (0.5-3.4 nmol/l). There were no significant differences in diurnal variation and between follicular and luteal phases. The range of androstenedione levels in untreated or poorly controlled CAH patients (7.6-355.0 nmol/l, median 42.5 nmol/l, n = 20) were significantly higher (p < 0.001) than the upper normal limit of 3.4 nmol/L for prepubertal children. The normal androstenedione reference ranges for paediatric and adult groups have thus been established.