All recipients of hematopoietic cell transplantation (HCT) are at risk for late endocrine and metabolic dysfunction as a complication of the chemoradiotherapy given before HCT. However, these disturbances are often multifactorial. This chapter will focus on the endocrine and metabolic problems that arise predominantly as a result of chronic graft versus host disease (cGVHD) or therapies used to treat cGVHD (Table 26.1).

BONE METABOLISM

The two major iatrogenic complications of cGVHD that involve the skeleton are reduced bone mineral density and avascular bone necrosis (AVN).

Osteopenia and Osteoporosis

Definitions and Incidence

Dual energy x-ray absorptiometry (DEXA) is now the most common method for measuring bone mineral density (BMD). In adults, osteopenia is present when BMD in g/cm2 equates to a T-score of –1.0 to –2.4 standard deviations (SD) below mean BMD values for healthy young adults. Osteoporosis is present when the T-score is less than or equal to –2.5. In children, T-scores are not used because the DEXA scan will detect area-related increases in BMD associated with increased bone volume during normal growth and development leading to over diagnosis of osteoporosis. Instead, SD scores for children must be normalized according to age-related mean BMD values, giving rise to z-scores.

One prospective study found that 46% of adults had osteopenia or osteoporosis at 12 months after HCT. Other studies have shown that half of children have reduced BMD after HCT.