Bone mineral density and quantitative ultrasound in adults with cystic fibrosis

Abstract

Objective: With increasing life span osteoporosis becomes a more recognized problem in patients with cystic fibrosis (CF). The aim of this cross-sectional study in 75 adult patients with CF (mean age 25.3 years) was to assess the prevalence of low bone mineral density (BMD) by dual-energy x-ray absorptiometry (DEXA) and, for the first time, by quantitative ultrasound (QUS), and to identify predicting factors. Design and Methods: Bone status was assessed at the lumbar spine (L2-L4) and the femoral neck by DEXA, and at the calcaneus by QUS (stiffness index). These data were correlated with a variety of clinical and anthropomorphic variables. Biochemical markers of bone turnover such as osteocalcin, bone-specific alkaline phosphatase, crosslinks in urine, 25-hydroxy vitamin D (25-OH vitamin D), parathyroid hormone, calcium and free testosterone were determined by standard assays. Results: The mean BMD T score (^S.E.M.) was 21:4^0:17 at the lumbar spine, and 20:54^0:16 at the femoral neck. The mean T score of the calcaneal stiffness index was 20:83^0:19: Based on a lumbar spine T score ,22.5 by DEXA, 27% of the patients had osteoporosis. Multiple regression analysis showed that the forced expiratory volume in one second (FEV 1 ) and the use of oral glucocorticoids were independent predictors of low lumbar spine BMD, whereas body mass index (BMI) and the use of oral glucocorticoids were independent predictors of low femoral neck BMD. The stiffness index correlated moderately with BMD (0.49-0.62, P , 0:0001). QUS had a sensitivity and specificity of only 57% and 89% respectively for diagnosing 'osteoporosis' (based on a femoral neck T score ,22.5 by DEXA). Positive and negative predictive values were 36% and 95% respectively. Conclusions: Low BMD is frequent in adults with CF and is most strongly correlated with disease severity (BMI, FEV 1 ) and the use of glucocorticoids. Calcaneal QUS might help to screen out patients with a normal BMD, but sensitivity and specificity were not sufficiently high to replace DEXA in these patients.

Failure of High-Dose Ergocalciferol to Correct Vitamin D Deficiency in Adults with Cystic Fibrosis

“…The exact prevalence depends on the threshold used to define "deficient." Studies using a threshold of less than 15 ng/ml estimate the prevalence of deficiency to be 30 to 40% (5,20). Using a threshold of less than 20 ng/ml results in approximately 50 to 60% being deficient (15).…”

Prevalence of low bone mineral density in adolescents and adults with cystic fibrosis

“…Low BMD has been independently associated with malnutrition, male sex, ΔF508 mutation, and severe lung injury 14 . Other potential risk factors described were use of glucocorticosteroids, hypogonadism, decreased physical activity, malabsorption of calcium and vitamins, chronic infections, and inflammatory cytokines 5,8,11,17,18,[20][21][22][23] .…”

The importance of monitoring bone metabolism markers and vitamin D in adult patients with cystic fibrosis

“…Было определено значительное изменение костного обмена -повы шение процессов резорбции при малой трансформа ции со стороны формирования костной ткани, что отражалось в выраженном увеличении β CrossLaps и нормальных или несколько сниженных показате лях остеокальцина. Схожие результаты были получе ны в других исследованиях у больных МВ [3,[7][8][9][10][11]. Это свидетельствует о дисбалансе и асимметричнос ти костного обмена с превалированием костной ре зорбции.…”

“…Тем не менее не была выявлена взаимосвязь уровня 25(ОН)D с дозой панкреатических ферментов, нали чием цирроза печени, ИМТ. Как и в других исследо ваниях [8,14,18], не определена корреляция уровня 25(OH)D c МПК.…”