Endocrine Abstracts

Introduction: First described in 1944, the condition is a rare pediatric genetic disease estimated to affect 1 in 48 000 individuals. Kallmann syndrome is an uncommon hereditary disorder and is among the most frequent cause of isolated congenital hypogonadotropic hypogonadism (CHH). In its classical form, it is characterized by hypogonadotropic hypogonadism and anosmia/hyposmia. Absent endogenous GnRH-induced LH pulsations occur due to failure of neuronal migration of the luteinizing hormone-releasing hormone (LHRH)-secreting neurons and the neurons of the vomeronasal nerve.

Case report: We report a case of a 15-year-old female teenager who presented to the endocrinology department for evaluation of delayed puberty. On further elicitation of medical history, she complained of anosmia, and on examination, no other significant past medical or surgical history was noted. On further inquiry, her maternal grandfather was a color blind.

Investigations: Evaluation of hypogonadism with a hormonal assay of FSH, LH, and testosterone, along with a GnRH stimulation test, revealed their serum concentrations to be below the normal limits; LH 0.20 mIU/mL (normal range: 1.7–15.0) and FSH =1.08 mIU/L (normal range: 1.9–11.6 mIU/L). With these biochemical investigations, keeping the diagnosis of KS in view, further workup was initiated and an MRI brain with contrast was suggested to look for olfactory tracts in particular and rule out any intracranial pathology.

Radiological findings: MRI brain with contrast revealed the absence of an olfactory bulb in the anterior cranial fossa and olfactory sulcus. The gyrus rectus and medial orbital gyrus formed a single gyrus. These findings were best appreciated on T2W coronal images. Imaging findings were typical for Kallmann’s syndrome. The rest of the brain was unremarkable, with no other abnormalities detected. With the relevant clinical picture, biochemical investigations showing low gonadotropic hormonal assays, and MR imaging features of absent olfactory tracts and hypoplastic olfactory sulcus, the diagnosis of KS was confirmed.

Genetics: Genetic workup was sent which suggested FGFR1 mutation (heterozygous variant). It is reported as the culpable mutation for kallmann syndrome with autosomal dominant transmission. The patient was treated with conjugated estrogens for hypogonadism.