Van Wyk–Grumbach syndrome

Discussion:

The patient's chronological age was 7 years 11 months. The hormonal laboratory investigations revealed:

  • TSH > 100 μIU/mL (0.35 - 4.94)
  • FT4 < 2.05 pmol/l (9.74 - 17.1)
  • FT3 = 1.31mol/l (4.1 - 7.9)
  • prolactin level = 140.90 ng/mL (2.8 - 29.2)
  • estradiol (E2) = 82.34 pg/mL (6 - 27)
  • FSH = 3.83 mUI/mL (0.3 - 2.8)
  • LH < 0.01 mUI/mL (0.1 - 6.0)

This case shows the characteristic features and hormonal profile seen in Van Wyk-Grumbach syndrome:

  • chronic hypothyroidism (usually due to autoimmune thyroiditis) with a very high TSH level
  • precocious puberty 
  • delayed bone age

The Van Wyk-Grumbach syndrome is considered as the only entity in which precocious puberty is associated with a delayed bone age, usually due to long-standing hypothyroidism.1.

The hyperprolactinemia is due to 1:

  • thyrotrophic hyperplasia of the pituitary gland (as in this case), compressing the pituitary stalk with a secondary disruption of the hypothalamic inhibition of the prolactin
  • or direct stimulation by TRH of the prolactin release

The precocious puberty may be related to the high levels of the circulating TSH which acts directly on the FSH receptor resulting in elevation of the estrogen production, which is responsible for the development of secondary sexual characteristics 2.

 

Additional contributor: ZE. Boudiaf, MD; CHU Constantine, Algeria

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