Endocrine Abstracts

Introduction: Bone densitometry is currently one of the mainstays in the evaluation of systemic bone diseases. The most frequently assessed densitometric parameter is areal bone mineral density (BMD), measured by dual energy X-ray absorptiometry (DEXA) and expressed as g/cm². However BMD is a bone size-dependent measure and may be found inappropriately low in children and adults with short stature. Osteopenia/osteoporosis have been described in patients with short stature due to growth hormone insensitivity syndrome (GHIS) caused by mutations in the GH receptor gene or its downstream mediators. Estimated volumetric bone density (BMAD), expressed as g/cm³, is thought to be more accurate than DEXA in interpreting areal bone density in GHIS patients.

Case report: A 47-years-old woman was admitted to our clinic for investigation of premenopausal osteoporosis. She had performed a DEXA due to bone pains, which revealed severe osteoporosis (lumbar spine T-score:−2.9, femoral neck T-score:−3). On physical examination she had short stature (1.47 cm) with normal BMI, thin lips and small chin. She had no previous history of intrauterine growth retardation. Hormonal investigation for short stature, revealed elevated level of basal serum GH concentration in repeated measurements, while IGF-1 and IGF-BP3 values were low, supporting a diagnosis of partial growth hormone insensitivity syndrome. No other hormone disorders were identified except mild elevation of FSH/LH and mild vitamin D insufficiency. The rest of the laboratory tests were normal. X-ray of lumbar and thoracic spine revealed no fracture. Estimated BMAD at the spine and femoral neck indicated osteopenia (lumbar spine T-score:−1.94, femoral neck T-score:−2.32). She was treated with vitamin D and calcium supplements.

Conclusion: The described case highlights the difficulties in the appropriate assessment of bone density in patients with short stature and partial GHIS. The use of the right technique is of great importance in order to avoid over treatment of these patients.