ISSN: 1308-5727 | E-ISSN: 1308-5735
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Turkish Society for Pediatric Endocrinology and Diabetes
High-Dose Hook Effect in 17-Hydroxyprogesterone Assay in a Patient with 21-Hydroxylase Deficiency [J Clin Res Pediatr Endocrinol]
J Clin Res Pediatr Endocrinol. 2015; 7(4): 329-332 | DOI: 10.4274/jcrpe.2180

High-Dose Hook Effect in 17-Hydroxyprogesterone Assay in a Patient with 21-Hydroxylase Deficiency

Mesut Parlak1, Hamit Yaşar Ellidağ2, Doğa Türkkahraman1
1Antalya Education And Research Hospital, Clinic Of Pediatric Endocrinology, Antalya, Turkey
2Antalya Education And Research Hospital, Clinic Of Biochemistry, Antalya, Turkey

Congenital adrenal hyperplasia (CAH) describes a group of disorders characterized by enzyme defects in adrenal steroidogenesis. 21-hydroxylase deficiency (21-OHD) is the most commonly encountered form. The analysis of steroids in pediatric cases requires high-sensitivity assays. A 14-year-old Syrian girl was referred for evaluation of short stature, amenorrhea, and hirsutism. On physical examination, breast development was Tanner stage 1. She had a phallic clitoris with a single urogenital orifice. Laboratory findings revealed primary adrenal deficiency with high androgen levels and low levels of 17-hydroxyprogesterone (17-OHP), (<0.05 ng/mL) and estrogen. This unexpected result led to suspicion of a high-dose hook effect. The measurement was repeated after 1/10 dilution of serum, and a high level of 17-OHP (115.4 ng/mL) was detected with the same test-enzyme-linked immunosorbent assay (ELISA). Simple virilizing form of CAH (21-OHD) was suspected and confirmed with genetic analysis. After initiation of glucocorticoid therapy, breast development was noted along with a decrease in testosterone level and an increase in estrogen level. To our knowledge, this is the first case report of hook effect for 17-OHP immunoassay in a patient with 21-OHD. High-dose hook effect should be suspected in patients with CAH when the test results are incompatible with one another. Additionally, this case demonstrates that a high testosterone level can block aromatase activity and consequently also estrogen production and breast development.

Keywords: High-dose hook effect,17-hydroxyprogesterone,immunoassay,congenital adrenal hyperplasia

Mesut Parlak, Hamit Yaşar Ellidağ, Doğa Türkkahraman. High-Dose Hook Effect in 17-Hydroxyprogesterone Assay in a Patient with 21-Hydroxylase Deficiency. J Clin Res Pediatr Endocrinol. 2015; 7(4): 329-332
Manuscript Language: English
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