Peter Bettembuk

The Effects of Pregnancy and Lactation on Bone Mineral Density

We performed a prospective study of bone mineral density (BMD) in 38 women during their first full-term pregnancy until 12 months postpartum. BMD measurements at lumbar spine [L2–L4 (LS)] and forearm [distal 33% (RD) and ultradistal (RUD) region of the radius] were made within 3 months before conception, after delivery, and at 6 and 12 months postpartum. In mid-pregnancy the DXA examination was carried out only at the forearm. Patients were grouped according to duration of lactation as group I, II or III (0–1, 1–6, 6–12 months respectively). During pregnancy there was a significant difference between baseline and delivery (p< 0.001) in the LS, RUD and RD BMD values. In group I there was no statistically significant difference in LS BMD between visits following pregnancy. The RUD BMD loss was recovered by 6 months postpartum (PP6). Group II showed continuous bone loss from delivery until PP6 at LS and RUD. In group III the LS BMD loss continued throughout the lactation period. The RUD BMD dropped (4.9%) until PP6 then increased by 3.0% as measured at 12 months postpartum (PP12). There was no significant change in RD BMD in any of three groups during lactation. At LS bone loss between delivery and PP12 correlated well with the duration of lactation (r=−0.727; p<0.001). We suggest that calcium needed for fetal skeletal growth during pregnancy was gained from maternal trabecular and cortical sites and that calcium needed for infant growth during lactation was drawn mainly from the maternal trabecular skeleton in our patients. The effect of pregnancy and lactation on the maternal bone mass was spontaneously compensated after weaning.

The effects of pregnancy and lactation on hormonal status and biochemical markers of bone turnover

INTRODUCTION Biochemical markers of bone turnover are reliable indices for measuring changes in bone formation and bone resorption. Due to limitations in the use of bone densitometry during pregnancy biochemical markers of bone turnover provide an excellent alternative to examine the state of the skeleton during this physiologic state. STUDY DESIGN We performed a prospective study in 20 women, during their first full term pregnancy until 12 months postpartum, intending to breast feed for 12 (mean, 9.1; range, 7-12) months postpartum. Morning blood and urine samples were obtained for laboratory tests: within 3 months before conception (baseline); between 22 and 24 gestational weeks; after delivery, and 6 and 12 months postpartum. Serum 25-hydroxyvitamin D (25-OH-D), parathyroid hormone (PTH), bone specific alkaline phosphatase, osteocalcin (OC), procollagen I carboxypeptides, calcium, phosphate and creatinine in addition to urine deoxypyridinoline crosslinks and calcium were measured. RESULTS There was no significant difference in the values of urinary calcium/creatinine and serum calcium, phosphate and 25-OH-D between the different visits during the study. In our patients there was a significant increase in PTH levels at 12 months postpartum as compared to baseline, although the mean values remained in the PTH reference range. All bone turnover markers increased during pregnancy and failed to reach baseline level even 12 months postpartum. CONCLUSION The high maternal bone turnover may suggest that the calcium needed for infant growth during pregnancy and lactation may be drawn at least in part from the maternal skeleton.

Pregnancy in women with systemic lupus erythematosus

BACKGROUND Systemic lupus erythematosus (SLE) is an autoimmune disorder which may be affected by hormonal changes, such as those of pregnancy. Women with SLE have increased adverse pregnancy outcomes. STUDY DESIGN A retrospective analysis of the gynecologic and immunologic case history of 140 women with SLE and the outcome of 263 pregnancies in 99 women with SLE. RESULTS In patients diagnosed with SLE, the proportion of pregnancies ending with live birth at term decreased to one-third compared with three quarters in those without a diagnosis of SLE and the incidence of pre-term deliveries and spontaneous abortions increased by 6.8 and 4.7 times, respectively. When SLE was associated with secondary antiphospholipid (APL) syndrome, and lupus anticoagulant (LA) or beta2-glycoprotein antibodies were present, a further increase in the incidence of pregnancy loss was observed. Pregnancy did not cause a flare-up of SLE in all cases, the disease remained stable in about 30% of the patients. Lupus was mild in the majority of the women who carried out their pregnancy to term. We also observed mothers with active SLE who successfully carried out pregnancies to term. CONCLUSION These findings accord with previous literature and should inform rheumatologists, obstetricians and neonatologists who guide patients in their reproductive decisions.

Bone mineral density in women with systemic lupus erythematosus

Abstract:The aim of this cross-sectional study was to determine the prevalence of reduced bone mineral density (BMD) in a group of female SLE patients and to identify factors predictive of reduced BMD. Femoral neck (FN) and lumbar spine (LS) dual-energy X-ray absorptiometry results were evaluated in 79 pre- and postmenopausal women with SLE aged (mean, range) 49 (22–73) years). Variables evaluated were disease duration, SLEDAI, current and cumulative corticosteroid dose, Steinbrocker’s functional classification, use of immunosuppressive agents, and history of fracture due to minor trauma. A T-score of ≤1.0 was found in 61.9% at the LS and 48.3% at the FN, and 18 (23.7%) patients belonged to the category of osteoporosis at LS, compared to only three (5.4%) patients at FN. A statistical difference (P= 0.014) was found when comparing LS BMD in pre- and postmenopausal patients. LS BMD had a significant correlation with daily and cumulative steroid dose (P= 0.016 and 0.031, respectively). There was a significant difference in LS BMD between the daily steroid dose group receiving ≤7.5 and those receiving >7.5 mg/day (P= 0.008), and also in FN BMD comparing groups on 0 and >7.5 mg/day (P= 0.022). There was significant difference in LS and FN BMD between patients in Steinbrocker classes I and III (P= 0.016 and 0.005, respectively). No significant correlation was found in either subgroup between BMD and other studied parameters. We concluded that the prevalence of reduced bone mass at LS is pronounced among postmenopausal women with SLE, in those with a high Steinbrocker functional classification and those on a high daily steroid dose. Therefore, these patients should be considered as a high-risk group deserving regular spinal BMD scans and therapy in time to prevent vertebral fractures.

Osteoporosis in mixed connective tissue disease

The existence of osteoporosis in 58 postmenopausal women with mixed connective tissue disease (MCTD) was investigated. The mean bone mineral density assessed by dual energy X-ray absorptiometry in the lumbar spine was decreased in 25.8% of the patients, reflecting osteoporosis (T score < −2.5). In the femoral neck there was no significant difference between the BMD of MCTD patients and that of age-matched, healthy postmenopausal women. Low bone mineral density was found among patients on, as well as off, corticosteroids. The extent of bone loss was associated with disease duration, as well as corticosteroid therapy. Serum osteocalcin levels were lower in MCTD patients than in controls. Lower serum oestradiol, testosterone and dehydroepiandrosterone sulphate levels were detected in MCTD patients than in controls. Thus, MCTD may be associated with increased bone loss. Pathogenic factors may include the disease itself, corticosteroid therapy, impaired osteoblast function, and low serum sex hormone levels.