What is the management for a patient with galactorrhea, fatigue, menorrhagia, elevated Thyroid-Stimulating Hormone (TSH), normal Thyroxine (T4), and mildly elevated Prolactin levels?

Management: Levothyroxine First, Then Reassess

The correct management is levothyroxine (option 2) to treat the primary hypothyroidism, which is the underlying cause of both the galactorrhea and the patient's symptoms. 1, 2, 3

Why Levothyroxine is the Priority

Primary hypothyroidism is driving the hyperprolactinemia in this patient. The elevated TSH with normal T4 indicates subclinical hypothyroidism, and the prolactin level of 800 (just below the upper limit of 870) represents mild hyperprolactinemia that is characteristic of hypothyroidism. 2, 3

• Hypothyroidism causes hyperprolactinemia through increased TRH (thyrotropin-releasing hormone), which stimulates both TSH and prolactin secretion. 2, 4
• In primary hypothyroidism, prolactin levels are typically modestly elevated and rarely exceed 100 ng/mL (though the units in your case may differ), making this presentation consistent with thyroid-induced hyperprolactinemia. 2
• Treating the hypothyroidism with levothyroxine will normalize both TSH and prolactin levels, resolving the galactorrhea without need for dopamine agonists. 2, 3

Treatment Algorithm

Step 1: Initiate Levothyroxine

• Start levothyroxine at approximately 1.6 mcg/kg/day for patients under 70 years without cardiac disease. 1
• For patients over 70 or with cardiac disease, start with 25-50 mcg/day and titrate gradually. 1
• The goal is to normalize TSH to 0.5-4.5 mIU/L, which will simultaneously normalize prolactin levels. 1, 5

Step 2: Monitor Response

• Recheck TSH and free T4 in 6-8 weeks after initiating therapy. 1
• Also measure prolactin at this time to confirm it is decreasing with thyroid hormone replacement. 2, 3
• Galactorrhea should resolve as prolactin normalizes with adequate thyroid replacement. 3

Step 3: Adjust Dose as Needed

• Titrate levothyroxine in 12.5-25 mcg increments based on TSH response. 1
• Continue monitoring every 6-8 weeks until TSH is stable in the target range. 1

Why NOT the Other Options

Cabergoline (Option 1) - WRONG

• Cabergoline is unnecessary because the hyperprolactinemia is secondary to hypothyroidism, not a primary prolactin disorder. 2, 4
• Treating the underlying hypothyroidism will resolve the hyperprolactinemia without dopamine agonist therapy. 3
• Using cabergoline would be treating the symptom rather than the cause and exposes the patient to unnecessary medication side effects. 4

Pituitary MRI (Option 3) - PREMATURE

• MRI is not indicated at this time because the prolactin level is only mildly elevated and within the range expected for hypothyroidism. 2, 4
• Pituitary imaging would be appropriate if prolactin remained significantly elevated (>100 ng/mL or equivalent) after thyroid function is normalized. 2, 4
• The combination of elevated TSH with mild hyperprolactinemia strongly suggests hypothyroidism as the primary etiology, making MRI unnecessary initially. 2

Observe and Reassess (Option 4) - INAPPROPRIATE

• Observation is inappropriate because the patient has symptomatic hypothyroidism (fatigue, menorrhagia, galactorrhea) with elevated TSH. 1
• Even with TSH in the subclinical range, symptomatic patients should be treated. 1, 5
• Delaying treatment risks progression to overt hypothyroidism and continued symptoms affecting quality of life. 1

Critical Pitfalls to Avoid

• Never start cabergoline before correcting hypothyroidism in patients with elevated TSH and mild hyperprolactinemia. 2, 4
• Do not order pituitary MRI for mild hyperprolactinemia (<100 ng/mL or equivalent) when hypothyroidism is present. 2, 4
• Avoid undertreating or delaying treatment in symptomatic patients, as this negatively impacts cardiovascular function, lipid metabolism, and quality of life. 1
• Approximately 25% of patients on levothyroxine are unintentionally maintained on excessive doses that suppress TSH, so monitor carefully to avoid overtreatment. 1

Expected Outcome

With appropriate levothyroxine therapy, expect normalization of TSH within 6-8 weeks, followed by resolution of hyperprolactinemia and galactorrhea. 1, 3 The menorrhagia and fatigue should also improve as thyroid function normalizes. 1