Korean J Intern Med.  2015 May;30(3):335-344. 10.3904/kjim.2015.30.3.335.

Reference interval for thyrotropin in a ultrasonography screened Korean population

• Kim M
• Kim TY
• Kim SH
• Lee Y
• Park SY
• Kim HD
• Kwon H
• Choi YM
• Jang EK
• Jeon MJ
• Kim WG
• Shong YK
• Kim WB

• KMID: 2160706
• DOI: http://doi.org/10.3904/kjim.2015.30.3.335

Abstract

BACKGROUND/AIMS
The diagnostic accuracy of thyroid dysfunctions is primarily affected by the validity of the reference interval for serum thyroid-stimulating hormone (TSH). Thus, the present study aimed to establish a reference interval for TSH using a normal Korean population.
METHODS
This study included 19,465 subjects who were recruited after undergoing routine health check-ups. Subjects with overt thyroid disease, a prior history of thyroid disease, or a family history of thyroid cancer were excluded from the present analyses. The reference range for serum TSH was evaluated in a normal Korean reference population which was defined according to criteria based on the guidelines of the National Academy of Clinical Biochemistry, ultrasound (US) findings, and smoking status. Sex and age were also taken into consideration when evaluating the distribution of serum TSH levels in different groups.
RESULTS
In the presence of positive anti-thyroid peroxidase antibodies or abnormal US findings, the central 95 percentile interval of the serum TSH levels was widened. Additionally, the distribution of serum TSH levels shifted toward lower values in the current smokers group. The reference interval for TSH obtained using a normal Korean reference population was 0.73 to 7.06 mIU/L. The serum TSH levels were higher in females than in males in all groups, and there were no age-dependent shifts.
CONCLUSIONS
The present findings demonstrate that the serum TSH reference interval in a normal Korean reference population was higher than that in other countries. This result suggests that the upper and lower limits of the TSH reference interval, which was previously defined by studies from Western countries, should be raised for Korean populations.

Keyword

Thyrotropin; Reference values; Thyroid microsomal antibodies; Ultrasonography; Smoking

MeSH Terms

Adult
Age Factors
Aged
Biomarkers/blood
Case-Control Studies
Cross-Sectional Studies
Female
Humans
Male
Middle Aged
Predictive Value of Tests
Reference Values
Republic of Korea
Sex Factors
Smoking/blood
Thyroid Diseases/blood/*diagnosis/ultrasonography
Thyroid Function Tests/*standards
Thyroid Gland/*metabolism/*ultrasonography
Thyrotropin/*blood
Time Factors
Young Adult
Biomarkers
Thyrotropin