An Objective Olfactory Evaluation and Its Correlation with MRI Findings in Asian Indian Patients with Idiopathic Hypogonadotropic Hypogonadism
Jagtap VS, Sarathi V, Lila AR, Nair S, Bukan A, Sankhe SS, Shivane V, Bandgar T, Menon P, Shah NS. Endocr Pract. 2013 Mar 19:1-18. [Epub ahead of print]


Department of Endocrinology, Seth GS Medical College, Maharashtra, India.


Objective: Idiopathic hypogonadotropic hypogonadism (IHH) can be associated with subnormal sense of smell. The objective of our study is to correlate olfactory phenotype (clinical smell test) of IHH patients and structural abnormalities in the olfactory apparatus on magnetic resonance imaging (MRI).Methods: This is single center prospective case control study. Forty one IHH patients underwent (a) brief smell identification test (UPSIT) and (b) MRI of the olfactory apparatus. The size of olfactory sulcus and bulb was quantified and compared with the normative data obtained in 40 controls. The agreement between UPSIT and MRI was assessed using kappa index.Results: Of the 41 patients, MRI showed normal (n=17), hypoplastic (n=14) and aplastic (n=10) olfactory apparatus. All 13 patients who complained of anosmia and 12 out of 28 patients who stated normosmia had low score on UPSIT. Thus 25 patients had Kallmann's syndrome (KS) and 16 were normosmic IHH (nIHH). Sixty eight percent of KS and 37.5 % of nIHH have abnormalities on MRI. The MRI abnormalities in KS were aplasia (56%) and hypoplasia (44%). All 6 nIHH patients with abnormal MRI had hypoplasia. There is (a) significant positive correlation (r = 0.61; p<0.01) between the olfactory bulb volume [MRI] and smell test scores (b) good agreement (kappa index: 0.72) between anosmia and aplastic olfactory apparatus.Conclusions: Self reporting of sense of smell significantly underestimates olfactory phenotype and hence, we recommend an objective smell test to distinguish KS from nIHH. Olfactory phenotype correlates well with MRI quantification of olfactory apparatus in IHH.