Biochemical evidence: positive effect of oral contraceptives on bone metabolism
| Study design | Reference | No of patients | OC exposure | Measurement of bone metabolism | Results |
|---|---|---|---|---|---|
| OC, Oral contraceptive; RCT, randomised controlled trial; EE, ethinyl oestradiol; NTx, N-telopeptides; D-PYR, deoxypyridinoline; BSAP, bone specific alkaline phosphatase; PYR, pyridinoline; Cr, creatinine. | |||||
| Oligo/amenorrhoeic | |||||
| RCT (level 1b) | Grinspoon et al91 | 45 women with hypothalamic amenorrhoea (ages 18–40) | OC group (35 μg EE+0.18 mg norgestimate, days 1–7; 35 μg EE+0.215 mg norgestimate, days 8–14; 35 μg EE+0.25 mg norgestimate, days 15–21) (n = 25) v placebo (n = 20) for 3 months | NTx, D-PYR | Decrease in NTx and D-PYR in OC treated group (therefore decreased resorption) |
| Healthy premenopausal | |||||
| RCT (level 1b) | Pinter et al93 | 41 women (ages 20–27) | 30 μg EE+150 μg levonorgestrel (n = 21) v control (n = 20) for 3 months | Serum BSAP and osteocalcin, urinary D-PYR | OC treated: BB genotype, decrease in osteocalcin; in Bb genotype, decrease in BSAP and osteocalcin; bb genotype, no change. Control: no changes in any genotype |
| Cohort (level 2b) | Paoletti et al94 | 30 women (ages 22–30) | 20 μg EE+75 μg gestodene (n = 10) v 30 μg EE+75 μg gestodene (n = 10) v control (n = 10) for 12 months | Urinary PYR, D-PYR | Decrease in PYR, D-PYR in OC-treated groups (suggesting decreased resorption) |
| Kitai et al95 | 30 women (mean age 23.7 years) | OC users v non-users | Urinary Ca2+/Cr ratio | Decrease in Ca2+/Cr with OC use (suggesting decreased resorption); effect more pronounced in non-smokers | |