ORANGE, CA — Patients with nondialysis-dependent chronic kidney disease (NDD-CKD) have a disproportionately higher prevalence of hypothyroidism compared with their non-CKD counterparts. That’s why researchers sought to determine the association between thyroid status, defined by serum thyrotropin (TSH) levels, and mortality among a national cohort of patients with NDD-CKD.
Results of the study involving 227,422 veterans with Stage 3 NDD-CKD were published in the journal Mayo Clinic Proceedings. A team led by University of California Irvine School of Medicine researchers with involvement from the Memphis VAMC focused on one or more TSH measurements from Oct. 1, 2004, to Sept. 30, 2012.1
Researchers first examined the association of thyroid status, defined by TSH categories of less than 0.5, 0.5 to 5.0 (euthyroidism) and more than 5.0 mIU/L, with all-cause mortality, then evaluating six granular TSH categories: less than 0.1, 0.1 to less than 0.5, 0.5 to less than 3.0, 3.0 to 5.0, more than 5.0 to 10.0, and more than 10.0 mIU/L. At the same time, the group examined thyroid status, thyroid-modulating therapy, and mortality in sensitivity analyses.
Results after analysis indicated that, compared with euthyroidism, baseline and time-dependent TSH levels of more than 5.0 mIU/L were associated with higher mortality (adjusted hazard ratios [aHRs] [95% CI], 1.19 [1.15-1.24] and 1.23 [1.19-1.28], respectively), as were baseline and time-dependent TSH levels of less than 0.5 mIU/L (aHRs [95% CI], 1.18 [1.15-1.22] and 1.41 [1.37-1.45], respectively).
In addition, researchers reported that granular examination of thyroid status suggested that incrementally higher TSH levels of 3.0 mIU/L or more were associated with increasingly higher mortality in baseline and time-dependent analyses, and TSH categories of less than 0.5 mIU/L were associated with higher mortality (reference, 0.5-<3.0 mIU/L) in baseline analyses.
“In time-dependent analyses, untreated and undertreated hypothyroidism and untreated hyperthyroidism were associated with higher mortality (reference, spontaneous euthyroidism), whereas hypothyroidism treated-to-target showed lower mortality,” they noted.
Calling for interventional studies identifying the target TSH range associated with the greatest survival in patients with NDD-CKD, study authors concluded, “Among U.S. veterans with NDD-CKD, high-normal TSH (≥3.0 mIU/L) and lower TSH (<0.5 mIU/L) levels were associated with higher death risk.”
1Rhee CM, Kalantar-Zadeh K, Ravel V, Streja E, You AS, Brunelli SM, Nguyen DV, Brent GA, Kovesdy CP. Thyroid Status and Death Risk in US Veterans With Chronic Kidney Disease. Mayo Clin Proc. 2018 May;93(5):573-585. doi:10.1016/j.mayocp.2018.01.024. PubMed PMID: 29728200.