Thyroid Dose Calculator

Levothyroxine dose from TSH and body weight.

Medical Disclaimer

This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.

Inputs

Body Weight (kg)

TSH (mIU/L)

Free T4 (ng/dL)

Patient Type (0=Young, 1=Elderly/Cardiac)

Tab to move between fields

Results

Calculated Dose (µg/day)

112

Nearest Tablet (µg)112

Recommended Starting Dose (µg)112

Dose Adjustment (µg)18.75

TSH Status (0–3)2

Free T4 Status (0–2)1

How to Use This Calculator

Enter Body Weight (kg), TSH (mIU/L), and Free T4 (ng/dL).
Select Patient Type (Young healthy adult or Elderly/Cardiac) — cardiac patients start at a lower dose.
Review Calculated Dose (ug/day) and the Nearest Available Tablet strength.
Check Recommended Starting Dose — initiate at 25-50 ug/day in elderly or cardiac patients.
Note TSH Status and Free T4 Status to guide dose adjustment at the 6-8 week recheck.

How the result changes with Body Weight (kg)

Body Weight (kg)	Calculated Dose (µg/day)
39	62.4
112	179.2
199	318.4
271	433.6

What each input means

Body Weight (kg): Patient body weight in kilograms.
TSH (mIU/L): Thyroid-stimulating hormone level. Normal range 0.4–4.0 mIU/L.
Free T4 (ng/dL): Free thyroxine level. Normal range 0.8–1.8 ng/dL.
Patient Type (0=Young, 1=Elderly/Cardiac): 0 = young healthy adult (1.6 µg/kg); 1 = elderly or cardiac patient (start low at 25 µg).

What each result means

Calculated Dose (µg/day): Weight-based full replacement dose (1.6 µg/kg for young adults, 1.0 µg/kg for elderly/cardiac).
Nearest Tablet (µg): Closest standard levothyroxine tablet size.
Recommended Starting Dose (µg): Starting dose considering patient type. Elderly/cardiac start at 25 µg regardless of target.
Dose Adjustment (µg): Suggested dose change based on current TSH. Positive = increase, negative = decrease, 0 = at goal.
TSH Status (0–3): 0 = Suppressed (<0.4), 1 = Normal (0.4–4.0), 2 = Subclinical hypo (4–10), 3 = Overt hypo (>10).
Free T4 Status (0–2): 0 = Low (<0.8), 1 = Normal (0.8–1.8), 2 = High (>1.8).

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Body Weight (kg) = 70, TSH (mIU/L) = 8, Free T4 (ng/dL) = 1, Patient Type (0=Young, 1=Elderly/Cardiac) = 0 = 4 input(s) provided
Calculate Calculated Dose
Calculated Dose = weightKg * dosePerKg
112 = 112
Calculate Nearest Tablet
Nearest Tablet
112 = 112
Calculate Recommended Starting Dose
Recommended Starting Dose
112 = 112