L-thyroxine Malabsorption Due to Calcium Carbonate Impairs Blood Pressure, Total Cholesterolemia, and Fasting Glycemia

[helvella]

Just in case anyone thinks that advice to separate calcium (and iron) from levothyroxine is a figment of our imaginations, have a look at this paper.

Not only does the paper make a point about separating taking of calcium and levothyroxine, by a long time, but they emphasise that doctors, including endocrinologists, are widely unaware. And that TSH test alone is inadequate. They also specifically identified the impact on cholesterol, blood sugar, and blood pressure.

Endocrine

. 2019 May;64(2):284-292.

doi: 10.1007/s12020-018-1798-7. Epub 2018 Oct 27.

L-thyroxine Malabsorption Due to Calcium Carbonate Impairs Blood Pressure, Total Cholesterolemia, and Fasting Glycemia

Elisabetta Morini 1 , Antonino Catalano 1 , Antonino Lasco 1 , Nunziata Morabito 1 , Salvatore Benvenga 2 3 4

• PMID: 30368654

• DOI: 10.1007/s12020-018-1798-7

Abstract

Purpose:

Calcium carbonate was previously shown to interfere with L-thyroxine absorption. To estimate the magnitude of tablet L-thyroxine malabsorption caused by calcium carbonate, with resulting increase in serum thyrotropin (TSH), we performed a cohort study in a referral care center.

Methods:

Fifty postmenopausal hypothyroid L-thyroxine-treated women (age 71.7 ± 5.1 years) who added calcium supplementation (600-1000 mg/day) were considered. They were taking L-thyroxine 45-60 min before breakfast (setting 1). After 4.4 ± 2.0 years from initiation of L-thyroxine therapy, they took calcium supplemaentation within 2 h after L-thyroxine taking (setting 2) for 2.3 ± 1.1 years. Hence, we recommended postponing calcium intake 6-8 h after L-thyroxine (setting 3). We evaluated TSH levels, the prevalence of women with elevated TSH (>4.12 mU/L), total cholesterolemia, fasting glycemia, blood pressure, and the prevalence of hypercholesterolemia, hyperglycemia, and hypertension.

Results:

TSH levels were 3.33 ± 1.93 mU/L versus 1.93 ± 0.51 or 2.16 ± 0.54 comparing setting 2 with setting 1 or 3 (P < 0.001, both). In setting 2, 18% women had elevated TSH versus none in setting 1 or 3 (P < 0.01). Total cholesterolemia, fasting glycemia, systolic, and diastolic blood pressure were also significantly higher in setting 2 compared to settings 1 and 3. For every 1.0 mU/L increase within the TSH range of 0.85-6.9 mU/L, total cholesterolemia, glycemia, systolic, and diastolic blood pressure increased by 12.1, 3.12 mg/dL, 2.31, and 2.0 mmHg, respectively.

Conclusions:

Monitoring of hypothyroid patients who ingest medications that decrease L-thyroxine absorption should not be restricted to solely measuring serum TSH.

Keywords: Blood pressure; Calcium carbonate; Fasting blood glucose; Hypothyroidism; L-thyroxine malabsorption; Serum cholesterol.

Abstract here.

pubmed.ncbi.nlm.nih.gov/303...

Full paper is behind a paywall here:

link.springer.com/article/1...

[jimh111]

You can walk around the paywall here researchgate.net/publicatio... .