Low Free T3 Is Associated With Worse Outcomes in Patients in the ICU Requiring Invasive Mechanical Ventilation.

OBJECTIVE: Critical illness causes a decrease in serum free triiodothyronine (T3) levels. This condition, known as nonthyroidal illness syndrome (NTIS), is associated with poor outcomes. The association of NTIS and outcomes in patients in the intensive care unit (ICU) requiring mechanical ventilation has not been well studied. This study aimed to determine the impact of NTIS on the outcomes of these patients. METHODS: This prospective study included 162 patients in the ICU who underwent mechanical ventilation. Serum free T3 levels were tested on the day of initiation of mechanical ventilation. The rates of in-hospital mortality and ventilator-free days (VFDs) at day 28 after the initiation of mechanical ventilation were compared between patients with low (<2.3 pg/mL) and normal (≥2.3 pg/mL) free T3 levels. Patients who died while on mechanical ventilation were assigned a VFD of 0. RESULTS: Low T3 was present in 60% of study patients. The in-hospital mortality rate of the entire cohort was 39%, and the mean and median VFDs at day 28 were 13.5 and 21 days, respectively. Compared to patients with normal free T3, patients with low free T3 had higher in-hospital mortality (52% vs 19%, P < .001) and less mean and median VFDs at day 28 (10.7 vs 18 and 0 vs 23, respectively. P < .001 for both mean and median VFDs). CONCLUSIONS: The presence of low T3 due to NTIS in patients in the ICU requiring mechanical ventilation is associated with poor outcomes.

Usefulness of Serum Triiodothyronine (T3) to Predict Outcomes in Patients Hospitalized With Acute Heart Failure.

Thyroid hormone plays an important role in cardiac function. Low levels of serum triiodothyronine (T3) due to nonthyroidal illness syndrome may have adverse effects in heart failure (HF). This study was designed to assess the ability of T3 to predict in-hospital outcomes in patients with acute HF. In total, 137 patients without thyroid disease or treatment with drugs which affect TH levels, who were hospitalized with acute HF were prospectively enrolled and studied. TH levels were tested upon hospital admission, and outcomes were compared between patients with low (<2.3 pg/ml) and normal (≥2.3 pg/ml) free T3 levels as well as between those with low (<0.6 ng/ml) and normal (≥0.6 ng/ml) total T3 levels. Low free T3 correlated with an increased length of stay in the hospital (median 11 vs 7 days, p <0.001) and higher rates of intensive care unit admission (31.8% vs 16.9%, p = 0.047), with a trend toward increased need for invasive mechanical ventilation (9.0% vs 1.4%, p = 0.056). Low total T3 correlated with an increased length of stay in the hospital (median 11 vs 7 days, p <0.001) and increased need for invasive mechanical ventilation (9.8% vs 1.3%, p = 0.045). In conclusion, low T3 predicts worse hospital outcomes in patients with acute HF and can be useful in the risk stratification of these patients.

Differences in affiliative behavior, pair bonding, and vaginal cytology in two species of vole (Microtus ochrogaster and M. montanus).

Prairie voles (Microtus ochrogaster) and montane voles (M. montanus) display marked differences in social organization in the field. Trios of 1 male and 2 females were studied in a large enclosure for a 10-day period. Prairie voles spent 59% of the observation time in side-by-side contact, whereas montane voles spent only 7% of the time in contact. Vaginal smears indicated female-female suppression of estrus in prairie voles; female montane voles appeared to cycle in the presence of males. Male prairie voles preferentially paired and nested with 1 of the females, and vaginal estrus generally followed pair formation by 2 days. Male montane voles did not spend time preferentially with either female, even after mating. These results suggest that the contrasting mating systems of these species result from differences in the propensity for affiliative behavior and social bonding rather than from mate availability or female receptivity.