Primary Hyperparathyroidism: The Influence of Bone Marrow Adipose Tissue on Bone Loss and of Osteocalcin on Insulin Resistance.
OBJECTIVE
Bone marrow adipose tissue has been associated with low bone mineral density. However, no data exist regarding marrow adipose tissue in primary hyperparathyroidism, a disorder associated with bone loss in conditions of high bone turnover. The objective of the present study was to investigate the relationship between marrow adipose tissue, bone mass and parathyroid hormone. The influence of osteocalcin on the homeostasis model assessment of insulin resistance was also evaluated.


METHODS
This was a cross-sectional study conducted at a university hospital, involving 18 patients with primary hyperparathyroidism (PHPT) and 21 controls (CG). Bone mass was assessed by dual-energy x-ray absorptiometry and marrow adipose tissue was assessed by 1H magnetic resonance spectroscopy. The biochemical evaluation included the determination of parathyroid hormone, osteocalcin, glucose and insulin levels.


RESULTS
A negative association was found between the bone mass at the 1/3 radius and parathyroid hormone levels (r = -0.69; p<0.01). Marrow adipose tissue was not significantly increased in patients (CG = 32.8±11.2% vs PHPT = 38.6±12%). The serum levels of osteocalcin were higher in patients (CG = 8.6±3.6 ng/mL vs PHPT = 36.5±38.4 ng/mL; p<0.005), but no associations were observed between osteocalcin and insulin or between insulin and both marrow adipose tissue and bone mass.


CONCLUSIONS
These results suggest that the increment of adipogenesis in the bone marrow microenvironment under conditions of high bone turnover due to primary hyperparathyroidism is limited. Despite the increased serum levels of osteocalcin due to primary hyperparathyroidism, these patients tend to have impaired insulin sensitivity.
Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Medicina Interna, Ribeirao Preto/SP, Brazil.
Maira L
ML
Mendonça
Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Medicina Interna, Ribeirao Preto/SP, Brazil.
Sérgio L
SL
Batista
Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Medicina Interna, Ribeirao Preto/SP, Brazil.
Marcello H
MH
Nogueira-Barbosa
Universidade de São Paulo, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Departamento de Física, Ribeirão Preto/SP, Brazil.
Carlos E G
CE
Salmon
Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Medicina Interna, Ribeirao Preto/SP, Brazil.
Francisco J A de
FJ
Paula
D015502:Absorptiometry, Photon; D050156:Adipogenesis / Q000502:physiology; D000273:Adipose Tissue / Q000000981:diagnostic imaging / Q000378:metabolism*; D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D015519:Bone Density / Q000502:physiology; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000378:metabolism*; D002118:Calcium / Q000097:blood; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006706:Homeostasis; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood*; D010281:Parathyroid Hormone / Q000097:blood; D012016:Reference Values
D001786:Blood Glucose; D010281:Parathyroid Hormone; D015675:Osteocalcin; D002118:Calcium