Clinicohormonal Parameters as a Primary Step to Differentiate Normosmic Idiopathic Hypogonadotropic Hypogonadism and Kallmann Syndrome in a Tertiary Care Hospital in Eastern India

Introduction: Idiopathic hypogonadotropic hypogonadism is a rare gonadal dysgenesis in which puberty does not take place naturally. It occurs due to insufficient pulsatile secretion of Gonadotrophin-Releasing Hormone (GnRH) and the resulting Follicle-Stimulating Hormone (FSH) and Luteinising Hormone (LH) deficiency leads to absence of or delayed sexual maturation. Kallmann syndrome is an uncommon genetic disorder characterised by hypogonadotropic hypogonadism associated with anosmia or hyposmia. When anosmia is absent, the same is referred as normosmic Idiopathic Hypogonadotropic hypogonadism (nIHH). Aim: To find out the significant differences between Kallmann syndrome and nIHH based on clinical features and biochemical assessment as a primary measure to initiate the treatment early. Materials and Methods: This hospital based cross-sectional observational cohort study was conducted in Department of Endocrinology, Nilratan Sircar Medical College and Hospital, Kolkata, India. The study was done on 55 cases of IHH presenting to the department with delayed secondary sexual characteristics. Results: Out of these 55 cases, 45 (81.8%) were of nIHH and only 10 (18.2%) cases were of Kallmann Syndrome. It was found that both the conditions show male predominance. Smell abnormalities were present only in Kallmann group. The level of serum testosterone was significantly higher (p<0.05) in nIHH subjects (mean-35.59 ng/dL) than patients with Kallmann Syndrome (mean-14.90 ng/dL). Patients with Kallmann syndrome showed significantly reduced pubic and axillary hair development and absence of gonadal development. Conclusion: Absence of puberty with anosmia/hyposmia with low serum FSH and LH, drastically reduced serum testosterone, are factors that point towards the diagnosis of Kallmann syndrome even in absence of genetic study, which is helpful for initiation of hormone replacement therapy for treatment.