Endocrine Imaging
Live dataThyroid Volume (Ellipsoid)
Estimates single-lobe and total thyroid volume from ultrasound lobe dimensions using the ellipsoid formula, to grade goitre and guide radioiodine or surgical planning.
The thyroid lobe approximates a prolate ellipsoid, so its volume is the product of the three orthogonal diameters and a correction factor of 0.529 (ฯ/6 โ 0.524 in idealised form; 0.529 is the empirically validated coefficient). The isthmus is conventionally excluded. Total gland volume is the sum of both lobes; when only one lobe is measured, a symmetric gland can be approximated by doubling.
๐งฎ Interactive Calculator
๐ Formula
Lobe volume (mL) = length ร width ร depth ร 0.529; total โ right lobe + left lobe
๐ฏ When to Use
- Grading diffuse goitre and monitoring change over time.
- Dosimetry planning before radioiodine therapy for hyperthyroidism or non-toxic goitre.
- Pre-operative sizing and assessment of retrosternal extension risk.
โ๏ธ How It Works
- Measure each lobe in three planes: craniocaudal length, transverse width and anteroposterior depth (cm).
- Compute lobe volume = length ร width ร depth ร 0.529.
- Sum the right and left lobe volumes (excluding the isthmus) for total gland volume.
- If only one lobe is measured, doubling gives an estimate for a grossly symmetric gland.
๐ Interpreting the Result
- Normal adult total volume is roughly 7โ10 mL in women and 8โ11 mL in men (upper reference limit commonly cited near 18 mL for women and 25 mL for men).
- Total volume >18 mL (women) / >25 mL (men) indicates goitre.
- Serial change of a discrete nodule or the whole gland is more informative than a single reading.
โ ๏ธ Limitations & Pitfalls
- The 0.529 coefficient is a population approximation; irregular or multinodular glands deviate from the ellipsoid model.
- Retrosternal or very large glands may extend beyond the sonographic field, causing underestimation.
- Operator-dependent caliper placement introduces measurement variability of up to 10โ15%.
๐ References
- Brunn J, Block U, Ruf G, et al. Volumetric analysis of thyroid lobes by real-time ultrasound. Dtsch Med Wochenschr. 1981;106(41):1338-1340.
- Ozgen A, Erol C, Kaya A, et al. Interobserver and intraobserver variations in sonographic measurement of thyroid volume. Eur J Endocrinol. 1999;140(6):505-509.
โ๏ธ For clinical decision support only. Always verify calculations and apply clinical judgment.