The increasing use of dietary supplements has led to questions about their potential impact on clinical testing, particularly thyroid function tests (TFTs). Many individuals take collagen supplements for skin, hair, and joint support, raising concerns about interference with the accurate measurement of thyroid hormones. Standard laboratory assessments rely on highly sensitive chemical reactions that can be disrupted by substances present in the bloodstream. Understanding the difference between a physiological effect and laboratory interference is necessary for correct interpretation of test results.
Identifying the Potential Interfering Ingredient
The collagen protein itself is rarely the cause of skewed thyroid test results. Collagen is a large protein broken down into amino acids when ingested. The actual source of interference is Biotin (Vitamin B7), a compound often included in multi-ingredient collagen products.
Many collagen formulas are fortified with high doses of Biotin to promote hair and nail strength. Supplements frequently contain milligram doses (up to 10 mg or more), far exceeding the microgram-level recommended daily intake. This pharmacological dose of Biotin, not the collagen peptides, causes laboratory error by disrupting the testing technology.
How Biotin Skews Thyroid Test Results
Standard thyroid function tests (TSH, Free T4, and Free T3) are performed using immunoassay technology. This method relies on the strong bond between Biotin and a protein called streptavidin to capture and measure hormones in a blood sample.
When excess Biotin from supplements is present, it floods the test environment and saturates the streptavidin binding sites. This prevents the assay’s reagents from binding correctly, disrupting the chemical reaction. The resulting measurement is therefore inaccurate because the excess supplement has chemically blocked the test’s ability to count the actual hormone concentration.
Interpreting Falsely Elevated or Lowered Results
The way Biotin interference affects results depends on the specific immunoassay design used for each hormone. For TSH, measured with a “sandwich” immunoassay, excess Biotin prevents the TSH-antibody complex from fully forming. This interference leads to a falsely lowered TSH result.
Conversely, Free T4 and Free T3 are measured using a “competitive” immunoassay, where excess Biotin causes a falsely high reading. This combination of falsely low TSH and falsely high T4/T3 mimics hyperthyroidism or Graves’ disease. This pattern could potentially lead a clinician to misdiagnose a condition or inappropriately adjust medication.
Preparation for Accurate Thyroid Testing
To avoid misleading thyroid test results, patients must temporarily stop taking any Biotin-containing supplements before their blood draw. The general recommendation is to stop the supplement for a minimum of 48 to 72 hours (two to three days). This time frame allows the excess Biotin to clear from the bloodstream.
While lower doses may require only eight hours, abstaining for the full 72 hours is recommended for maximum accuracy. Patients must also inform their healthcare provider and the lab technician about all supplements being consumed, especially those promoting hair, skin, and nail health. This communication ensures the lab can use a non-Biotin-based assay or correctly interpret anomalous results.
Does Collagen Itself Affect Thyroid Function
The concern about collagen is primarily due to laboratory interference from added Biotin, not a direct physiological effect of the protein on the thyroid gland. Collagen peptides are broken down into amino acids, such as glycine, which the body uses for various metabolic processes. These amino acids supply the building blocks necessary for protein synthesis, including the body’s own production of thyroid hormones. Consuming collagen protein is not known to directly increase or decrease the production of TSH or thyroid hormones. Adequate protein intake, including the amino acids found in collagen, is generally supportive of overall thyroid health.