A nationwide registry-based observational study of thyroid disease incidence in the Faroe Islands.

OBJECTIVE: The occurrence of thyroid disease varies among populations. While the iodine nutrition level of the Faroese seems to have been decreasing over the past decades, there is no systematic evaluation of the thyroid disease pattern in the Faroe Islands. Such knowledge of thyroid disease occurrence in the North Atlantic region may support healthcare planning and prevention. To investigate incidence rates, including subtypes of thyroid diseases, and demographic characteristics of thyroid disease patients in the Faroe Islands, to improve understanding of the patterns and trends of these disorders. DESIGN AND METHOD: A registry-based observational study was conducted over 10 years, encompassing all adult Faroese individuals. PATIENTS AND MEASUREMENTS: Health records from general practitioners and hospitals were used to identify incident cases of thyroid diseases. Validation was performed using multiple data sources. The incidence rates were standardised using population data from the middle of the study period 2006-2018. RESULTS: Among the 1152 individuals diagnosed with thyroid disease, the standardised incidence rates per 100,000 person-years were 55 for hyperthyroidism and 112 for hypothyroidism, and around four times higher in women than in men. Hashimoto's thyroiditis was the dominant cause of hypothyroidism, while Graves' disease was the leading cause of hyperthyroidism. The incidence of hypothyroidism increases with age. A decreasing trend was observed over time for both hypothyroidism and hyperthyroidism. CONCLUSION: Considering the decrease in iodine nutrition levels over the past decades, we were surprised by the high incidence of autoimmune thyroid disease. The findings highlight the need for continuous monitoring of thyroid disease occurrence in coastal areas of the North Atlantic Ocean.

The iodine content of Faroese food items to support iodine nutrition in the North Atlantic.

Iodine is essential for human health, and dietary iodine sources are critical. Living isolated on islands in the North Atlantic Ocean fostered unique dietary traditions in the Faroe Islands. The dietary peculiarities led us to collect and measure the iodine content of local foods and beverages and calculate daily iodine intakes based on four Faroese dietary scenarios. Marine foods and birds had iodine contents from 300 µg/kg and up, markedly higher than dairy, grains, terrestrial, vegetables, and liquid foods (p<0.001). Vegetables and beverages contained negligible iodine. Wind-dried fermented lamb meat iodine content varied by 100% depending on whether it was herded on an island with beaches (105 µg/kg) or with cliffs (53 µg/kg) facing the ocean. The daily iodine intake varied from around 50 µg to just over 200 µg with diets rich in fish and whales. In conclusion, the traditional diet has been a critical source of iodine on the Faroe Islands. The Faroese may be iodine replete with traditional diets but face the risk of iodine deficiency with dietary transition towards a more western diet. Locally produced Faroese foods are therefore relevant to promote health, and may additionally support food security, local involvement and knowledge, and long-term sustainability.

A nationwide study of autoimmune liver diseases in the Faroe Islands: Incidence, prevalence, and causes of death 2004 - 2021.

Background and aims: Autoimmune liver diseases are rare diseases, and population-based studies on the epidemiology of autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) are sparse. We aimed to assess the incidence of AIH, PBC, and PSC in the Faroe Islands.Methods: All cases of AIH, PBC, and PSC diagnosed in the Faroe Islands between January 1st, 2004, and December 31st, 2021, were included in this nationwide registry-based cohort study. In addition, we searched all medical records to assess diagnostic criteria and cause of death.Results: The incidences of AIH, PBC, and PSC in the Faroe Islands were 5.2, 2.5 and 0.7 per 100,000 population per year, respectively. Point prevalence per 100,000 population on December 31st 2021, was 71.8 for AIH, 38.5 for PBC, and 11.0 for PSC. Nine AIH patients died after a median of 3 years, three died of hepatocellular carcinoma (HCC), and two died of liver failure. Five PBC patients died after a median of 7 years, one of HCC and one of liver failure. One PSC patient died of cholangiocarcinoma.Conclusion: The incidence and prevalence of AIH, PBC and PSC in the Faroe Islands are among the highest reported in population-based settings.

Urine test strips and iodine contamination: a tricky trick in iodine nutrition surveys.

OBJECTIVE: A recent report from the Faroe Islands suggested mild iodine deficiency among women aged 40 years and older. New preliminary results showed an average urinary iodine concentration of 457 µg/L. This spurious finding encouraged the present report. METHODS: A subset of 17 consecutive pregnant women from an ongoing study provided an additional morning spot urine sample; one part was tested for a few seconds with a test strip for glucose, protein, and erythrocytes, and the other was left untouched. The women recorded the previous week's intake of iodine-rich foods. Additionally, 12 tap water samples were collected such that three samples were sealed immediately, the remaining were strip tested for 10, 30 and 60 s, respectively. Urine and water samples were analysed using the ceri/arsen method after alkaline ashing. RESULTS: Median urinary iodine concentration (UIC) in pristine urine samples was 116 µg/L (IQR 79-204 µg/L; range 26-475 µg/L), and positively associated with iodine-rich food intake. UIC increase with test-strip dip varied from 10 to 94 times the non-dip value. In tap water, the pristine samples had an iodine concentration of 2-4 µg/L, which increased to 10,000 µg/L after 60 s. CONCLUSION: Urine samples exposed to test strips can be contaminated within a few seconds leading to unreliable iodine results. Therefore, it is crucial that the study protocol clearly states the procedure for urine sample collection and handling, strict adherence to protocol, and that utensils used are dedicated to collecting urine to measure iodine.

Iodine nutrition among the adult population of the Faroe Islands: a population-based study.

The WHO recommends monitoring iodine status in all populations with median urinary iodine concentration (UIC) below 100 µg/l suggesting iodine deficiency. There are no data on the iodine intake among the population of the Faroe Islands. This study aimed to provide data on iodine nutrition in a representative sample of the general adult population from the Faroe Islands. We conducted a population-based cross-sectional survey in 2011-2012 and measured iodine in urine from 491 participants (294/197 men/women) using the ceri/arsen method after alkaline ashing. Participants include about 100 subjects in each of four adult decades and included participants from both the capital city and villages. The median UIC was low within the recommended range 101 µg/l (range 21-1870 µg/l). No samples were in the range suggesting severe iodine deficiency, but half of the samples were in the range of just adequate or mildly insufficient iodine intake with UIC markedly lower in women than in men (86 v. 115 µg/l; P < 0·001). Intake of fish and whale meals affected the UIC. In conclusion, nearly half of the population had an iodine excretion in the range of borderline or mild iodine deficiency. The lowest iodine nutrition level among Faroese women is a concern as it may extend to pregnancy with increased demands on iodine nutrition. In addition, we found that large variations and the intermittently excessive iodine intakes warrant follow-up on thyroid function in the population of the Faroe Islands.