What does the Iodine, Urine (inductively coupled plasma mass spectrometry) test measure?

Why is Iodine, Urine (inductively coupled plasma mass spectrometry) measured?

Urinary iodine is the preferred biomarker of population iodine status and the only practical measure of individual intake, though a single spot sample has limited precision due to biological and dietary variation. Low values support iodine deficiency as a contributor to hypothyroidism or goitre; high values may reflect excess supplementation. Interpretation is improved by concurrent thyroid function tests and by repeat sampling.

Reference ranges

Standard reference

WHO thresholds for population sufficiency: median urinary iodine 100–299 µg/L; individual spot values interpreted cautiously due to high day-to-day variation.

Functional medicine optimal

WHO guidance: 100–299 µg/L for population sufficiency; individual optimal ranges are less well defined, and values above 300 µg/L may indicate excessive intake.

Units

µg/L, µg/g creatinine

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.