Iodine is a trace mineral your body needs to produce thyroid hormones, which regulate metabolism, energy, and growth. Because iodine cannot be manufactured by the body, it must come from dietary sources including seafood, dairy, eggs, and iodised salt. In Australia, mild iodine insufficiency remains relatively common, particularly among people on restrictive diets or those who limit their intake of iodine-rich foods.
The spot urine iodine test is a quick screening tool that measures urinary iodine concentration from a single morning sample. Because most dietary iodine is excreted through the kidneys, urinary iodine concentration gives a reasonable indication of recent intake. Results are compared against WHO reference ranges that categorise intake as deficient, adequate, more than adequate, or excessive.
It is worth understanding the limitations of a single spot measurement. Urinary iodine fluctuates with hydration, time of day, and what you ate recently, so a single result is a snapshot rather than a definitive assessment. First morning urine provides the most consistent reading. For people with borderline results or those who want a more thorough picture of their total body stores, the iodine loading test is an option worth discussing with your practitioner.
This test is suited to anyone wanting a convenient first check of whether their dietary iodine intake appears adequate, people tracking changes after adjusting their diet, or those on restrictive eating patterns who may not be getting enough iodine. Your practitioner can interpret the result alongside thyroid function testing if a fuller picture is needed.
Suited to people who want a convenient initial screen of their iodine intake, those tracking the effect of dietary changes, or anyone on a restrictive diet who may not be getting enough iodine.
