90mg / 1 1/2 grain
90mg / 1 1/2 grain is a prescriber-directed compounded preparation prepared or dispensed for patient-specific use within the Hormone Optimization therapy area. Genesis should dispense this medication only pursuant to a valid prescription and the prescriber's clinical judgment.
This is a compounded thyroid hormone preparation at 90 mg (one and one-half grains), providing approximately 57 mcg levothyroxine (T4) and 13.5 mcg liothyronine (T3) based on the established grain ratio of 38 mcg T4 and 9 mcg T3 per 60 mg. This mid-range maintenance dose is appropriate for patients with primary hypothyroidism who have been titrated to this level. Genesis Compounding prepares this as a patient-specific, prescriber-directed 503A preparation; it is not FDA-approved as a compounded preparation.
| Active Ingredient | Pharmacologic Role |
|---|---|
| Levothyroxine (T4) ~57 mcg per 90 mg (1½ grain) | Prohormone T4 undergoes peripheral conversion to active T3 by iodothyronine deiodinases; T3 activates nuclear TRα/TRβ receptors, regulating metabolic rate, cardiac output, thermogenesis, and protein synthesis. |
| Liothyronine (T3) ~13.5 mcg per 90 mg (1½ grain) | Active thyroid hormone binding directly to nuclear TRα/TRβ with high affinity; produces thyromimetic effects approximately four-fold more potent per microgram than levothyroxine. |
Oral administration (capsule or tablet), taken on an empty stomach 30–60 minutes before the first meal.
- Swallow with water; do not crush or chew.
- Maintain ≥4-hour separation from calcium, iron, antacids, cholestyramine, and sucralfate.
90 mg (1½ grains) is a standard mid-range maintenance dose for adult hypothyroidism:
- Most patients require 60–120 mg/day maintenance; 90 mg is the midpoint of this range.
- At this dose, average serum concentrations of T4 and T3 should support near-normal TSH in most patients with primary hypothyroidism when dosed appropriately.
- TSH, free T4, and free T3 should be assessed at 4–6 weeks and annually thereafter.
- All dosing is prescriber-determined.
- Levothyroxine (T4): Hepatic and peripheral conversion to T3 by type 1/type 2 deiodinases; T3 binds TRα/TRβ nuclear receptors, activating transcription of genes governing metabolic rate, cardiac function, and thermogenesis.
- Liothyronine (T3): Direct high-affinity nuclear receptor agonist; produces rapid and sustained thyromimetic effects at approximately four-fold greater potency per microgram than T4.
The 90 mg (1½ grain) maintenance dose is used in the majority of adult hypothyroid patients who have completed initial titration. Key clinical considerations:
- Verify that TSH is within the target range (typically 0.5–2.5 mIU/L; individualized per prescriber).
- Reassess annually when stable; sooner after intercurrent illness, significant weight change, or medication changes that affect thyroid hormone metabolism.
- In elderly patients and those with cardiovascular disease, reassess cardiac status at each visit.
Contraindications:
- Untreated adrenal insufficiency; active thyrotoxicosis; acute MI; hypersensitivity to components.
Warnings & Precautions:
- Supratherapeutic dosing at this strength may cause palpitations, arrhythmia, and bone loss; monitor TSH carefully.
- Long-term TSH suppression below normal is associated with atrial fibrillation and osteoporosis.
- Biotin interference with immunoassays — hold ≥48 hours before labs.
Drug Interactions:
- Warfarin: thyroid hormones potentiate anticoagulant effect; monitor INR with any dose change.
- Calcium, iron, antacids, sucralfate: impair absorption significantly — 4-hour separation required.
Common Side Effects: At excess doses — tachycardia, palpitations, heat intolerance, weight loss, tremor, diarrhea, insomnia, and nervousness.
Store at room temperature (15–25°C), protected from light, heat, and excessive humidity. Keep tightly closed. Do not refrigerate. Keep out of reach of children. Use by the beyond-use date assigned by Genesis Compounding per USP <795>.
Is 1½ grain (90 mg) the right maintenance dose for me?
For many adults, 90 mg falls within the optimal maintenance range. Whether this is the right dose for you depends on your body weight, degree of hypothyroidism, and laboratory results. Your prescriber will confirm through TSH and free thyroid hormone monitoring.
How often do labs need to be checked at this dose?
Once your dose has been stable and your labs are within the target range, annual monitoring is generally appropriate. Recheck labs sooner if you experience symptoms of over- or under-treatment, change weight significantly, start new medications, or have intercurrent illness.
Is this preparation FDA-approved?
No. This is a patient-specific, 503A compounded preparation from Genesis Compounding, not an FDA-approved finished drug product.
What happens if I miss a dose?
Take the missed dose as soon as possible that morning; if it is already close to the next day, skip the missed dose and resume your regular schedule. Due to the relatively long half-life of T4, missing one dose occasionally has minimal clinical impact.
Should I be concerned about bone health at this dose?
At 90 mg, TSH should remain within the normal range for most patients, which does not carry the same fracture risk as TSH-suppressive therapy (used in thyroid cancer). Your prescriber will monitor your TSH to ensure it remains appropriately normal.
Clinical References
Authoritative sources reviewed in preparing this clinical summary. Provided for prescriber reference; not a substitute for the prescriber’s clinical judgment.