Jansen SW, et al. J Clin Endocrinol Metab. 2015;doi:10.1210/jc.2015-2624. August 5, 2015

In a family study in the Netherlands analyzing the hormone levels of children of nonagenarian parents with at least one long-lived sibling, researchers also found that familial longevity was not linked with pulsatile secretion of TSH. Further, although there was a strong temporal relationship between TSH and free triiodothyronine, there was no longevity link between TSH and free thyroxine.

Steffy Jansen, of the Department of Gerontology and Geriatrics at Leiden University Medical Center in the Netherlands, and colleagues analyzed data from 20 offspring of nonagenarian parents (10 men) with at least one long-lived sibling participating in the Leiden Longevity Study, along with 18 partners without long-lived parents as controls (10 men). All study participants were aged 55 to 78 years (mean age, 65 years).

Researchers sampled participants’ blood every 10 minutes for 24-hour TSH and hourly for thyroid hormone profiles. Participants were provided liquid meals at three fixed times during the day. Researchers assessed basal, pulsatile and other secretion parameters with deconvolution analysis to characterize ultradian rhythmicity, and locally weighted polynomial regression of TSH to assess circadian rhythmicity.

Researchers found that offspring of long-living parents had a higher mean basal TSH secretion compared with controls (34.3 vs. 18.5 mU/L/24 h; P = .001). Researchers found no differences in ultradian or circadian TSH properties. The temporal relationship between TSH and free triiodothyronine at zero delay was higher in offspring compared with controls (P = .05). There was no difference between groups in feedback and forward interplay between TSH and thyroid hormone.

“Remarkably, thyroid concentrations were similar in offspring and partners despite a 60% higher TSH secretion,” the researchers wrote. “This observation may be the result of either diminished biological activity of TSH, increased peripheral deiodinase activity or decreased sensitivity of the thyroid gland to TSH.”

Researchers said challenge experiments with TSH, thyroid hormone or a dopamine agonist are needed to better understand the association. by Regina Schaffer

Disclosure: The researchers report no relevant financial disclosures.