Exploring symptoms and signs of mild thyroid overactivity in Dutch primary care

Subclinical hyperthyroidism and TSH measurements in primary care in the Netherlands

Status

Active, not recruiting

Phases

Unknown

Study type

Observational

Source

ISRCTN

Registry ID

ISRCTN15496928

Enrollment

200

Registered

2023-05-25

Start date

2012-01-01

Completion date

Unknown

Last updated

2026-06-22

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Subclinical hyperthyroidism Nutritional, Metabolic, Endocrine

Interventions

A dataset will be extracted from the PHARMO general practitioner database (see https://pharmo.nl/) using routine care data. A nested case-control study will be performed. For every case (see inclusion

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: Cases: Patients with TSH concentration below reference range and with fT4 concentration within reference range (at same measurement) or patients with recorded ICPC code A91.07 (subclinical hyperthyroidism). Controls: TSH and fT4 measurement within reference range

Exclusion criteria

Exclusion criteria: Cases: 1. In 2 years prior to inclusion use of amiodarone (ATC C01BD01) 2. In 2 years prior to inclusion use of thyroid medication (ATC starting with H03) 3. Ever recorded use of lithium (ATC N05AN01) 4. In 2 years prior to inclusion mention of ICPC T85 (hyperthyroidism), T86 (hypothyroidism), A91.07 (subclinical hyperthyroidism), T71 (thyroid malignancy), A91.06 (subclinical hypothyroidism) Controls: During 5-year follow-up from cohort entry date: 1. TSH or FT4 measurement outside of reference range 2. Mention of ICPC codes (see also above) T85, T86, A91.07, T71, A91.06

Design outcomes

Primary

Measure	Time frame
Cardiovascular comorbidity and bone health. In the exploratory analyses the exact outcomes will be determined by means of International Classification of Primary Care (ICPC) codes, medication use (such as osteoporosis medication or medication used in heart failure) and relevant laboratory data (for example cholesterol and BNP values), the researchers will compare this comorbidity between the subclinical hyperthyroid group and controls using a dataset over the last 10 years (2012-2022).	—

Measure

Time frame

Cardiovascular comorbidity and bone health. In the exploratory analyses the exact outcomes will be determined by means of International Classification of Primary Care (ICPC) codes, medication use (such as osteoporosis medication or medication used in heart failure) and relevant laboratory data (for example cholesterol and BNP values), the researchers will compare this comorbidity between the subclinical hyperthyroid group and controls using a dataset over the last 10 years (2012-2022).

—

Secondary

Measure	Time frame
Natural course of subclinical hyperthyroidism by TSH and free T4 concentrations using a dataset over the last 10 years (2012-2022)	—

Countries

Netherlands

Outcome results

None listed

Source: ISRCTN (via WHO ICTRP) · Data processed: Jun 27, 2026