Geometry and bone mass in primary hyperparathyroidism assessed by peripheral Quantitative Computed Tomography (pQCT).
OBJECTIVE
Non-invasive measurement by peripheral quantitative computed tomography (pQCT) of bone geometry, biomechanics, and mineral content in patients (pts) with primary hyperparathyroidism (PHPT).


METHODS
Total, trabecular and cortical mineral density (totBMD, cortBMD, trab BMD), bone geometrical properties (total area, trabecular area, cortical area, cortical/total area) and cortical thickness as biomechanical parameters, were assessed by pQCT at distal radius in 38 (32 F; 6 M) consecutive patients with PHPT (mean age: 62 yrs; range: 30-77). In a subgroup of 12 patients, bone mineral density (BMD) was also measured by means of dual X-ray absorptiometry (DXA) at the lumbar spine (L2-L4).


RESULTS
Serum biochemical characteristics were: iPTH (269+/-214 pg/ml; range: 107-1438, normal: 30-65), Calcium (11.4+/-1.1 mg/dl; range: 10.6-13.5, normal: 8.1-10.4) and Alkaline Phosphatase (398+/- 392 U/L; range:173-1174, normal: 98-279). Compa-red with 87 healthy age-matched subjects, total, trabecular and cortical bone densities were reduced in all patients (TotBMD: 216+/-92 mg/cm(3) vs ctr 342+/-94, -37%, p<0.05; TrabBMD: 93+/-51 mg/cm(3) vs ctr 140+/-54, -34%, p <0.01; CorBMD: 711+/-178 mg/cm(3) vs ctr 802+/-175, -11%, p<0.02), such as cortical thickness (0.143+/-0.02 cm vs ctr 0.157+/-0.03, -9%, p<0.02). Among geometrical parameters, only cortical/total area was significant different in the two groups (0,29 vs 0.31; p<0.04). A strong correlation was found between peripheral trabecular bone density assessed by pQCT and axial bone mineral density measured by DXA at L2-L4 (r=0.80; p<0.01).


CONCLUSIONS
pQCT measurements in PHPT showed: 1) osteopoenia in all bone compartments partly related to age and menopause; 2) reduced cortical density and cortical thickness consistent with "cancellization" of the inner cortex and lower ability of bone to absorb loading forces. DXA measurements showed osteopoenia also at the lumbar spine, a site rich in trabecular bone. PQCT allowing selective assessment of true volumetric cortical and trabecular bone density such as bone geometry, is proposable in clinical practice, in order to evaluate presurgical bone "status" and to monitor the response to parathyroidectomy.
Di Leo
Claudio
C
Servizio di Medicina Nucleare, Cattedra e Scuola di Specializzazione in Medicina Nucleare, Ospedale S. Paolo, Università degli Studi di Milano, Milano, Italy. dilcladio@yahoo.it
Bestetti
Alberto
A
Bastagli
Amelia
A
De Pasquale
Loredana
L
Tagliabue
Luca
L
Bagni
Bruno
B
Pepe
Leonardo
L
Tarolo
Gian Luigi
GL
D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000469:Alkaline Phosphatase / Q000097:blood; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology*; D002118:Calcium / Q000097:blood; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D014057:Tomography, X-Ray Computed / Q000379:methods*
D010281:Parathyroid Hormone; D000469:Alkaline Phosphatase; D002118:Calcium