Objective:

To assess the differences in lipid metabolism parameters between patients with mild subclinical hypothyroidism treated or untreated with levothyroxine.

Approach:

• Study Design: Single-center, retrospective cohort study including patients with mild subclinical hypothyroidism not on thyroid hormone replacement therapy.
• Participants: Fifty-two patients with at least two measurements of TSH and lipid panel were analyzed.
• Endpoints: Primary endpoints were changes in TSH, total cholesterol, and LDL cholesterol between treated and untreated groups.

Key Findings:

• Fifty-twopatients(14treatedand38untreated)wereanalyzed.MedianbaselineTSHandLDL-cholesterolwere5.6mIU/Land121.0mg/dL,respectively.MedianTSHdecreasedsignificantlyinbothtreated(-2.5mIU/L)anduntreatedgroups(-1.7mIU/L)withp<0.001.Thetreatedgroupshowedsignificantincreasesintotalcholesterol(7.8mg/dL)andLDL-cholesterol(13.2mg/dL)withp=0.01andp=0.03,respectively.NochangeswereobservedinHDL-cholesterolandtriglyceridesforeithergroup.

Interpretation:

Levothyroxine therapy in patients with mild subclinical hypothyroidism was associated with increased total and LDL-cholesterol.

Limitations:

• Retrospective design limits causal inferences.
• Single-center study may affect generalizability.
• Exclusion of patients on lipid-lowering therapies may skew results.

Conclusion:

Levothyroxine therapy was associated with increased cholesterol levels in patients with mild subclinical hypothyroidism.