Kallmann syndrome

Kallmann syndrome (KS) is a rare genetic disorder characterized by hypogonadotropic hypogonadism associated with anosmia or hyposmia. When anosmia is absent it is simply referred to as idiopathic hypogonadotropic hypogonadism (IHH)

It is a rare disorder with an estimated prevalence of one in 10,000 males and one in 50,000 females 1,3. Both clinically and genetically Kallmann is heterogeneous, and although most cases are sporadic with all modes of inheritance been described 1,3.

Although patients with Kallmann syndrome are anosmic from birth, this usually is not apparent to either the parents or the child. The diagnosis is only made when puberty does not occur. At that time gonadotropin levels (FSH, LH, testosterone, and estradiol) are low, whereas other pituitary hormones are normal 3

Occasionally the diagnosis is made earlier due to investigation of other associated anomalies, including:

MRI is the modality of choice in assessing for the absence of olfactory bulbs, and coronal T2 sequences are most effective. The olfactory nerves, bulbs, and sulci are absent (arhinencephaly).

Importantly the hypothalamus and pituitary are normal in appearance. 

Treatment is primarily aimed at restoring normal pubertal development and in some case normal fertility. The former can be achieved by administration of exogenous sex steroids, appropriate to the gender of the patient. If fertility is desired, pulsed gonadotropin releasing hormone can be administered (with variable success) 3

It was first identified as a clinical entity by Franz Josef Kallmann, an German-born American psychiatrist, in 1944 4

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Article information

rID: 6084
Synonyms or Alternate Spellings:
  • Olfactogenital syndrome
  • Kallman syndrome
  • Kallmann's syndrome

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Cases and figures

  • Figure 1: Kallman versus normal anatomy
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  • Case 1
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