Bone resorption associated with uncoupling of osteoclastic and osteoblastic activities in adult T cell leukemia with hypercalcemia: case report

A 64-year-old woman with adult T cell leukemia (ATL) was admitted to our ho spital with severe hypercalcemia. The serum calcium level was elevated to 1 4.9 mg/dl. Biochemical parameters for bone formation including serum osteoc alcin (bone G1a protein, BGP) and alkaline phosphatase (ALP) were normal. T he serum levels of tartrate-resistant acid phosphatase (TRAP), a parameter for bone resorption, were increased (4.6 KAU). The serum level of parathyro id hormone-related protein (PTHrP) was elevated (343 pmol/l). The cytokines with stimulatory effects on bone resorption, such as interleukin (IL)-1 al pha, IL-1 beta, IL-6, and tumor necrosis factor-alpha, were not detected. S erum Ca levels, PTHrP levels, and TRAP levels decreased with the decrease i n ATL cells after chemotherapy, while serum BGP levels and ALP levels incre ased. On the 29th hospital day, ATL cells began to increase again. Then ser -um PTHrP levels, Ca levels, and TRAP levels increased, while serum BGP lev els and ALP levels decreased. A marked excessive bone resorption with suppr essed bone formation (uncoupling) occurred in this patient. The ATL cells p roduced not only PTHrP but also IL-1 alpha and IL-1 beta. These results sug gest that PTHrP may act as a humoral factor and IL-1 may act as a local fac tor in bone metabolism of ATL patients.