Metabolic bone disease in lumbar pseudarthrosis. Pseudarthrosis occurs in many patients who undergo lumbar spine fusion and it has been suggested that abnormalities of bone metabolism contribute to it. The authors evaluated 47 patients with pseudarthrosis for metabolic bone disease. Symptomatic patients with pseudarthrosis underwent metabolic bone evaluation. Abnormal results of laboratory tests were found in 7 patients (14.9%): 3 low or borderline 1,25 dihydroxy vitamin D3, 2 elevated 24-hour urine calcium, and 2 low serum testosterone. None of these abnormalities correlated with other clinical findings. Bone density was low in 14 of 24 patients in whom it was measured. Low values did not correlate with smoking or abnormal laboratory values. Metabolic bone abnormalities do not appear to play a frequent or significant role in pseudarthrosis after attempted lumbar spine fusion. 