X-Message-Number: 27420
Date: Thu, 8 Dec 2005 18:43:45 -0800 (PST)
From: Doug Skrecky <>
Subject: thyrotropin may extend human lifespan

JAMA 2004 Dec 1;292(21):2591-9
Thyroid status, disability and cognitive function, and survival in old
age.
  CONTEXT: Despite the equivocal outcomes of randomized controlled
trials, general clinical opinion favors screening and treatment of
elderly individuals with subclinical thyroid disorders. OBJECTIVES: To
determine whether subclinical thyroid dysfunction should be treated in
old age and the long-term impact of thyroid dysfunction on performance and
survival in old age. DESIGN, SETTING, AND PARTICIPANTS: A prospective,
observational, population-based follow-up study within the Leiden 85-Plus
Study of 87% of a 2-year birth cohort (1912-1914) in the municipality of
Leiden, the Netherlands. A total of 599 participants were followed up from
age 85 years through age 89 years (mean [SD] follow-up, 3.7 [1.4]
years). MAIN OUTCOME MEASURES: Complete thyroid status at
baseline; disability in daily life, depressive symptoms, cognitive
function, and mortality from age 85 years through 89
years. RESULTS: Plasma levels of thyrotropin and free thyroxine were not
associated with disability in daily life, depressive symptoms, and
cognitive impairment at baseline or during follow-up. Increasing levels
of thyrotropin were associated with a lower mortality rate that remained
after adjustments were made for baseline disability and health
status. The hazard ratio (HR) for mortality per SD increase of 2.71 mIU/L
of thyrotropin was 0.77 (95% confidence interval [CI], 0.63-0.94; P =
.009). The HR for mortality per SD increase of 0.21 ng/dL (2.67
pmol/L) of free thyroxine increased 1.16-fold (95% CI, 1.04-1.30; P =
.009). CONCLUSIONS: In the general population of the oldest old, elderly
individuals with abnormally high levels of thyrotropin do not experience
adverse effects and may have a prolonged life span. However, evidence for
not treating elderly individuals can only come from a well-designed,
randomized placebo-controlled clinical trial.

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