Bone histomorphometric analysis in a patient with anorexia nervosa

Area of Science:

• Nephrology
• Endocrinology
• Osteology

Background:

• Anorexia nervosa (AN) is associated with significant medical complications, including renal dysfunction and bone loss.
• Premenopausal osteoporosis in AN is not well-characterized histologically, especially when combined with kidney injury.

Observation:

• A 34-year-old woman with AN (BMI 11.0 kg/m²) presented with renal dysfunction (creatinine 1.8 mg/dL) and hypokalemia (3.0 mEq/L).
• Renal biopsy revealed chronic interstitial fibrosis and juxtaglomerular apparatus hypertrophy.
• Iliac crest biopsy showed active bone resorption, impaired mineralization, and osteocyte death, indicative of severe osteoporosis.

Findings:

• Histological analysis demonstrated active periosteal and endosteal resorption by osteoclasts and bone island formation.
• Dynamic bone histomorphometry indicated impaired mineralization correlating with nutritional status.
• Empty lacunae suggested osteocyte apoptosis, a novel finding in AN-related osteoporosis.

Implications:

• Malnutrition and hypokalemia in AN negatively impact bone formation by impairing mineralization and may activate osteoclast-mediated resorption.
• This case highlights the severe skeletal consequences of AN and provides the first histological description of premenopausal osteoporosis in a patient with AN and kidney injury.
• Recovery of bone mass and renal function following nutritional intervention underscores the importance of comprehensive management in AN.