What causes elevated SHBG (Sex Hormone-Binding Globulin) levels in men?

What Causes Your Elevated SHBG at 90 nmol/L

Your SHBG of 90 nmol/L is elevated, and the most likely causes in a lean 30-year-old man are hyperthyroidism, early liver disease, medications (anticonvulsants, thyroid hormone), smoking, or HIV—you need targeted testing to identify the underlying condition rather than attempting to lower SHBG directly. 1, 2, 3

Primary Causes to Investigate in Your Case

Given your age (30), lean body habitus (70kg, 182cm), and difficulty lowering SHBG, you should systematically evaluate these specific conditions:

Most Likely Culprits

• Hyperthyroidism or subclinical hyperthyroidism: This is a common cause of isolated SHBG elevation in young, lean men and is frequently missed because symptoms can be subtle 1, 3, 4

  • Get TSH, free T4, and free T3 measured immediately 3
  • Even subclinical hyperthyroidism significantly elevates SHBG 3

• Early hepatic disease: Liver dysfunction impairs SHBG metabolism, causing accumulation even before other liver function tests become abnormal 1, 3, 4

  • Check comprehensive liver function tests (AST, ALT, GGT, bilirubin, albumin) 3
  • SHBG rises in early liver disease but may paradoxically decline with progression to cirrhosis 3

• Medications: Review all medications including over-the-counter supplements 1, 3

  • Anticonvulsants (phenytoin, carbamazepine) 1, 4
  • Thyroid hormone replacement (levothyroxine) 1, 4
  • Estrogens or estrogen-containing compounds 1, 4

• Smoking: Active smoking is independently associated with elevated SHBG 1, 3

• HIV/AIDS: Should be tested in appropriate clinical contexts 1, 3

Why You Cannot Lower It

The fundamental issue is that SHBG elevation is a consequence, not a primary disease—treating the underlying condition is the only effective way to normalize SHBG levels. 2, 3

• Direct attempts to lower SHBG (through weight gain, insulin manipulation, or anabolic steroids) are inappropriate and potentially harmful when the underlying cause is unaddressed 1, 2
• Medications that decrease SHBG (growth hormone, glucocorticoids, testosterone, anabolic steroids) should only be used when clinically indicated for other conditions, not solely to lower SHBG 2

Clinical Significance of Your Elevated SHBG

Your elevated SHBG likely means you have reduced free testosterone despite potentially normal total testosterone: 2, 3

• SHBG binds testosterone with high affinity, reducing free and bioavailable testosterone 2
• The pituitary senses free testosterone, not total testosterone, so you may have compensatory elevation of LH and FSH 2
• You could be experiencing hypogonadal symptoms (low libido, erectile dysfunction, reduced muscle mass, fatigue) even if total testosterone appears normal 2, 3

Essential Testing You Need

Measure these simultaneously on a morning sample: 2, 3

• Total testosterone (using accurate assay, not immunoassay)
• Free testosterone (calculated or measured)
• LH and FSH
• TSH, free T4, free T3
• Comprehensive liver function tests
• Consider HIV testing based on risk factors

Diagnostic Algorithm

1. First priority: Rule out hyperthyroidism—this is the most common reversible cause in your demographic 3

   • If TSH is suppressed or free T4/T3 elevated, refer to endocrinology
   • Correcting hyperthyroidism will normalize SHBG 3

2. Second priority: Evaluate liver function comprehensively 3

   • If liver enzymes are elevated, pursue hepatology workup
   • Managing liver disease appropriately treats the underlying SHBG elevation 2

3. Third priority: Medication review and cessation trial if applicable 3

4. Fourth priority: Assess for symptomatic hypogonadism 2, 3

   • If free testosterone is low despite normal total testosterone, you may benefit from testosterone replacement
   • This addresses the consequences of high SHBG rather than the SHBG itself

Common Pitfalls to Avoid

• Do not rely solely on total testosterone measurements—elevated SHBG causes functional hypogonadism with low free testosterone despite normal total testosterone 2, 3
• Do not attempt to lower SHBG pharmacologically without identifying the cause—this masks the underlying problem and may cause harm 2
• Do not overlook subclinical thyroid disease—it significantly affects SHBG but may have minimal symptoms 3
• Do not assume age-related changes at 30 years old—while aging increases SHBG, this is more relevant after age 50 1, 3

If No Cause Is Found

If comprehensive evaluation reveals no identifiable cause and you have symptoms of testosterone deficiency with documented low free testosterone:

• Testosterone replacement may be appropriate even with normal total testosterone 2
• Monitor carefully with baseline and serial PSA, digital rectal exam, and hematocrit every 3-6 months initially 2
• Benefits include improved sexual function, well-being, muscle mass, and bone density 2