Hyperthyroidism and SHBG Levels
Yes, hyperthyroidism significantly increases sex hormone-binding globulin (SHBG) levels, and a value of 42 pmol/L may be elevated due to your thyroid condition. 1, 2
Relationship Between Hyperthyroidism and SHBG
Hyperthyroidism has a direct and well-documented effect on SHBG levels:
- Thyroid hormones increase hepatic production of SHBG, resulting in elevated serum SHBG concentrations in hyperthyroid states 2
- Research shows that SHBG levels are consistently elevated in patients with hyperthyroidism compared to euthyroid controls 3
- The degree of SHBG elevation correlates with the severity of hyperthyroidism, with higher levels seen in patients with higher free T3 and free T4 levels 4
Clinical Significance
The elevation of SHBG in hyperthyroidism has several important clinical implications:
- Altered free hormone levels: Increased SHBG binds more testosterone and estradiol, potentially reducing free (bioavailable) hormone levels despite normal or even elevated total hormone levels 1
- Diagnostic value: SHBG has been studied as a potential metabolic marker of thyroid function, with some researchers suggesting it could be used as an in vitro thyroid function test 4
- Treatment effects: When hyperthyroidism is treated successfully, SHBG levels gradually return to normal 1, 2
Evidence from Research
A 2019 study examining male patients with hyperthyroidism found:
- Before treatment, hyperthyroid patients had significantly elevated SHBG levels (146±111 nmol/L) 1
- After antithyroid drug treatment, SHBG levels decreased significantly as thyroid function normalized 1
- Free testosterone levels, which were initially low, increased as SHBG levels decreased 1
Another study demonstrated that:
- SHBG levels correlate positively with free thyroid hormone concentrations 2
- In hyperthyroid patients receiving antithyroid treatment, SHBG concentrations decreased significantly (p<0.01) 2
- After successful treatment, SHBG levels returned to those comparable with euthyroid controls 2
Monitoring and Management
If you have confirmed hyperthyroidism:
- Regular monitoring of thyroid function tests (TSH, free T3, free T4) is essential 5
- Treatment of the underlying hyperthyroidism with appropriate therapy (antithyroid medications, radioactive iodine, or surgery) will typically normalize SHBG levels over time 5, 1
- Beta-blockers may be used to control cardiac symptoms while definitive treatment takes effect 5
Important Considerations
- The duration of hyperthyroidism affects SHBG levels, with longer exposure to elevated thyroid hormones resulting in higher SHBG concentrations 6
- SHBG levels may remain elevated even in patients with biochemical hyperthyroidism who appear clinically euthyroid 4
- SHBG and corticosteroid-binding globulin (CBG) respond oppositely to thyroid status - while SHBG increases in hyperthyroidism, CBG decreases 2, 3
If you're concerned about your SHBG level of 42 pmol/L, discuss with your healthcare provider how this relates to your specific thyroid condition and whether additional hormone testing might be warranted.