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Open access

Bronwen E Warner, Carol D Inward and Christine P Burren

Summary

This case, presenting with bilateral impalpable testes, illustrates the relevance of a broad differential disorders of sex development case management. It provides new insights on hypothalamic–pituitary–gonadal (HPG) axis and testicular function abnormalities in the multisystem disorder of Lowe syndrome. Lowe syndrome, also known as oculocerebrorenal syndrome, is a rare disorder characterised by eye abnormalities, central nervous system involvement and proximal renal tubular acidosis. There are a handful of reports of pubertal delay, infertility and cryptorchidism in Lowe syndrome. Biochemistry aged 72 h: testosterone 6.4 nmol/L, LH <0.5 IU/L and FSH <0.5 IU/L. Gonadotropin-releasing hormone stimulation test identified significantly raised baseline LH = 45.4 IU/L (contrasts with earlier undetectable LH), with a 20% increase on stimulation, while baseline FSH = 4.3 IU/L with no increase on stimulation. Day 14 HCG stimulation test produced an acceptable 50% increase in testosterone. The constellation of further abnormalities suggested Lowe syndrome: hypotonia, bilateral cataracts (surgical extraction and intraocular lens implantation) and renal tubular acidosis (microscopic haematuria, hypercalciuria, proteinuria, generalised aminoaciduria, hypophosphataemia and metabolic acidosis). DNA sequencing identified de novo hemizygous frameshift mutation OCRL c.2409_2410delCT in exon 22. Interpretation of initial and repeat GnRH and HCG testing indicates the likelihood of testicular failure. Partial testicular descent occurred but left orchidopexy was required. Improving long-term gonadal function in Lowe syndrome assumes increased importance for current cohorts as advances in renal replacement therapy have greatly improved life expectancy. Noting HPG axis abnormalities in Lowe syndrome in infancy can identify cases requiring increased surveillance of pubertal progress for earlier detection and management.

Learning points:

  • Clinical endocrine problems in Lowe syndrome has been reported, but has focused on abnormalities in adolescence and young adulthood: pubertal delay and infertility.

  • We present an infant with isolated LH elevation at baseline and on GnRH stimulation testing who also had bilateral impalpable testes.

  • Early testing of the HPG axis in patients with Lowe syndrome may help predict gonadal abnormalities from a younger age, which will enhance the overall case management into adolescence.

Open access

Eline van der Valk, Tom Tobe, Aline Stades and Alex Muller

Summary

A 53-year-old male presented with recurrent calcium oxalate kidney stones as a first sign of underlying acromegaly, which vanished when his acromegaly was controlled. The exact mechanism behind hypercalciuria and urolithiasis in acromegaly is not yet clear. By discussing this case, a short overview of the pathophysiology of hypercalciuria in acromegaly and practical insights are given.

Learning points

  • Hypercalciuria is a common finding in acromegaly.

  • There are only few reports describing hypercalciuric kidney stones in acromegaly.

  • We assume that in acromegaly there is a primary role of IGF1-mediated, PTH-independent increase in calcitriol synthesis resulting in hypercalciuric kidney stones.