The calcium (Ca) metabolism of established human lactation was studied in 40 adult women (mean age 32.4 years) who had been breast-feeding for 6 months (Lac) and in 40 age-matched controls (Con) using fasting urine and blood biochemistry and forearm single-photon bone mineral densitometry (BMD). Serial studies were performed up to 6 months after weaning in Lac women and repeated once in Con women. During lactation the significant findings were (1) a selective reduction (7.1%, P less than 0.03) in BMD at the ultradistal site containing 60% trabecular bone, but not at two more proximal, chiefly cortical bone sites; (2) increased bone turnover affecting bone resorption [fasting hydroxyproline excretion, Lac 2.22 +/- 0.12 mumol/liter GF (mean +/- SEM), Con 1.19 +/- 0.04, P less than 0.001] and affecting bone formation (plasma alkaline phosphatase, Lac 81.9 +/- 2.5 IU/liter, Con 53.5 +/- 2.7, P less than 0.001, and serum osteocalcin, Lac 14.0 +/- 0.7 microgram/liter, Con 7.3 +/- 0.4, P less than 0.001); and (3) renal conservation in the fasting state of both Ca and inorganic phosphate (Pi) with a resultant moderate increase in plasma Pi but not in plasma Ca (total or ionized). There were no differences between the groups in serum parathyroid hormone (PTH, intact and midmolecule assays), 25-hydroxy- and 1,25-dihydroxyvitamin D, nephrogenous cyclic AMP production, or plasma creatinine.(ABSTRACT TRUNCATED AT 250 WORDS)

This study has shown a high prevalence of postpartum thyroid dysfunction but there was no difference in the clinical and psychiatric signs and symptoms between cases and controls. In the social, psychological, physical and endocrine setting of the postpartum period, women with postpartum thyroid dysfunction are identifiable by the attending physician only by their abnormal thyroid function tests.

No abstract

The fractional absorption of calcium (FA-Ca) was measured using a dual non-radioactive Ca isotope technique in 26 control women, 49 women in the last trimester (36 weeks) of pregnancy and 31 of these women in established (20 weeks) lactation. The ratio of the two non-radioactive Ca isotopes was measured, by high precision thermal ionisation mass spectrometry, in urine 12-24 hours after administration and was used to calculate FA-Ca. This is the first study to clearly show that FA-Ca is significantly elevated in late pregnancy but not in established lactation, when compared with control women.

OBJECTIVE To follow the clinical and biochemical course of a cohort of women who had postpartum thyroid dysfunction (PPTD) at 6 months postpartum and to examine the treatment practices of general practitioners and endocrinologists in the setting of PPTD. DESIGN Prospective longitudinal study. SETTING Metropolitan, Perth, Australia. PARTICIPANTS Eighty-six Caucasian women who were identified to have PPTD at 6 months postpartum in a cross-sectional study of 748 women.MAIN OUTCOME MEASURES Characteristics of the clinical and biochemical course of PPTD and documentation of the treatment practices and factors influencing treatment of PPTD by general practitioners and endocrinologists. RESULTSSixteen of 86 women (19%) were receiving treatment at 9 months postpartum and by 30 months postpartum 27% of women had received treatment for PPTD. Fifty-one percent of those not treated were biochemically euthyroid at 9 months, although, for those with hypothyroid biochemistry at 6 months, the median TSH at 18 months was at the upper limit of the reference range. Thyroid peroxidase antibody titre fell over the 2 years of follow-up. There was no significant change in clinical parameters over the study. Forty-nine percent of endocrinologists and 73% of general practitioners reported that they required clinical signs or symptoms before initiating treatment for hypothyroid PPTD. CONCLUSIONSIn a cohort of women with postpartum thyroid dysfunction, a quarter received treatment. Elevated TSH in untreated women does not completely return to the normal median. The role of clinical assessment in treatment decision-making differs between primary care physicians and endocrinologists. A case is made for the early Institution of permanent thyroxine replacement in women with postpartum thyroid dysfunction, elevated TSH and positive thyroid antibodies.Postpartum thyroid dysfunction (PPTD) is a phenomenon which occurs in a reported 3±11% of women in the first year after childbirth (Roti & Emerson, 1992). It is thought to be a benign, self-limiting, autoimmune disease in the majority of cases and is often not treated although it is recognized that many women later develop permanent hypothyroidism (Weetman, 1994).In our cross-sectional study at six months postpartum we have identified an 11´5% (CI 9´2±13´8) prevalence of PPTD (Kent et al., 1999). In this further study we have followed this cohort of women with PPTD to 30 months postpartum in order to determine the clinical and biochemical course of PPTD and its likelihood to recur in subsequent pregnancies. We have documented treatment in these women and also surveyed those practitioners most likely to encounter this problem ± general practitioners and endocrinologists ± in order to determine what factors prompt them to institute thyroxine therapy in this condition. Methods Design and sampleFrom a cross-sectional study of the prevalence of PPTD conducted in Perth in 1995, 86 women were identified with PPTD at 6 months postpartum (Kent et al., 1999). These women formed the cohort for a follow-up st...