Bone Mineral Content in Patients with Anaphylactic Reactions, Signs of Mastocytosis and Elevated Basal Serum Tryptase Levels

ABSTRACT

To examine the relationship between elevated basal serum tryptase levels (BST), a marker of total mast cell mass, and bone mineral density (BMD) in patients with anaphylactic reactions and signs of mastocytosis.

Retrospective evaluation of patient charts at an allergy unit. Patients with BST levels above 20 ng/ml were eligible if clinical and follow-up data and results of dual X-ray absorptiometry (DXA) were available. Patients with previous use of anti-osteoporotic medications and with osteoporosis not caused by mastocytosis were excluded. Spearman’s rank correlation, Mann-Whitney test and receiver operating characteristic curve (ROC) was used for analysis.

24 patients were included. The main presenting symptom (17 of 24 patients) was anaphylactic reactions to insect stings. BST levels ranged between 21 and 158 ng/ml (median 48 ng/ml). Study participants with Z-score values below - 1.0 had a median BST level of 46 ng/ml, the patients with Z-score values above or equal to -1.0 had a median BST level of 27 ng/ml. ROC analysis of the patient group with BST values between 30 and 100 ng/ml revealed a best cut-off value of BST to detect a low BMD when BST level would be at least 27 ng/ml resulting in a sensitivity of 92% and a specificity of 70%.

Patients with moderately elevated BST levels seem to be at increased risk for low BMD.