Chest
Volume 135, Issue 6, June 2009, Pages 1448-1454
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Original Research
Critical Care Medicine
Nonthyroidal Illness Syndrome and Prolonged Mechanical Ventilation in Patients Admitted to the ICU

https://doi.org/10.1378/chest.08-1816Get rights and content

Background

The effect of the nonthyroidal illness syndrome (NTIS) on the duration of mechanical ventilation (MV) has not been extensively investigated. This study aims to determine whether the NTIS is associated with the duration of MV in patients admitted to the ICU.

Methods

We evaluated all patients admitted over a 6-year period to our ICU who underwent invasive MV and had measurement of serum free triiodothyronine (fT3), free thyroxine (fT4), and thyroid-stimulating hormone (TSH) performed in the first 4 days after ICU admission and, subsequently, at least every 8 days during the time they received MV. The primary outcome measure was prolonged MV (PMV), which was defined as dependence on MV for > 13 days.

Results

Two hundred sixty-four patients were included. Fifty-six patients (normal-hormone group) had normal thyroid function test results, whereas 208 patients (low-fT3 group) had, at least in one hormone dosage, low levels of fT3 with normal (n = 145)/low (n = 63) levels of fT4 and normal (n = 189)/low (n = 19) levels of TSH. Patients in the low-fT3 group showed significantly higher mortality and simplified acute physiology score II, and significantly longer duration of MV and ICU length of stay compared with the normal-hormone group. Two of the variables studied were associated with PMV, as follows: the NTIS (odds ratio [OR], 2.25; 95% confidence interval [CI], 1.18 to 4.29; p = 0.01); and the presence of pneumonia (OR, 1.17; 95% CI, 1.06 to 3.01; p = 0.03).

Conclusion

The NTIS represents a risk factor for PMV in mechanically ventilated, critically ill patients.

Section snippets

Materials and Methods

Our institutional review board approved the protocol. Considering that the retrospective nature of the investigation focused on aspects of our usual clinical practice, the informed consent was waived.

Results

Figure 1 shows the stratification of patients according to their serum thyroid hormone tests results. Over a period of 72 months, 5,285 patients were admitted to our ICU. In 866 of these patients, serum TSH, T3, and T4 levels were measured at least once during their ICU stay. Of these patients whose hormone levels were measured, 731 patients were approached for participation in the study; 135 patients were found not to be eligible because they had not received MV for > 24 h and/or they had not

Discussion

The main result of this study was that NTIS is associated with a PMV. It still remains controversial whether the NTIS represents a protective or a maladaptive response to illness6, 8, 11, 25, 26 and whether the tissues of patients with NTIS are chemically hypothyroid or euthyroid.2, 6, 11, 25, 26 As some authors have noted,2, 26 a more specific cellular marker for hypothyroidism than those actually available would be needed. Even though this condition has been considered for many years as a

Acknowledgment

We thank Dr. Vincenzo Tracuzzi for his contributions to data collection and processing.

References (44)

  • GR Doran et al.

    The origin of the elevated activities of creatine kinase and other enzymes in the sera of patients with myxoedema

    Clin Chim Acta

    (1975)
  • MJ Hooper

    Diminished TSH: secretion during acute non-thyroidal illness in untreated primary hypothyroidism

    Lancet

    (1976)
  • F Bermudez et al.

    High incidence of decreased serum triiodothyronine concentration in patient with nonthyroidal disease

    J Clin Endocrinol Metab

    (1975)
  • L Wartofsky et al.

    Alterations in thyroid function in patients with systemic illnesses: the “euthyroid sick syndrome”

    Endocr Rev

    (1982)
  • IJ Chopra et al.

    Thyroid function in nonthyroidal illness

    Ann Intern Med

    (1983)
  • R Docter et al.

    The sick euthyroid syndrome: changes in thyroid hormone serum parameters and hormone metabolism

    Clin Endocrinol (Oxf)

    (1993)
  • B McIver et al.

    Euthyroid sick syndrome: an overview

    Thyroid

    (1997)
  • LJ De Groot

    Dangerous dogmas in medicine: the nonthyroidal illness syndrome

    J Clin Endocrinol Metab

    (1999)
  • IJ Chopra et al.

    Reciprocal changes in serum concentrations of 3,3′,5′-triiodothyronine (reverse T3) and 3,3′,5-triiodothyronine (T3) in systemic illnesses

    J Clin Endocrinol Metab

    (1975)
  • G Van den Berghe

    Novel insights into the neuroendocrinology of critical illness

    Eur J Endocrinol

    (2000)
  • EM Kaptein et al.

    Relationship of altered thyroid hormone indices to survival in nonthyroidal illness

    Clin Endocrinol (Oxf)

    (1982)
  • IJ Chopra

    Clinical review 86: euthyroid sick syndrome; is it a misnomer?

    J Clin Endocrinol Metab

    (1997)
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