What follow-up strategies should be implemented for patients diagnosed with thyroiditis to monitor for potential complications?

While the provided UK guidelines do not specifically detail follow-up strategies for 'thyroiditis' as a standalone diagnosis, they outline comprehensive monitoring for conditions that can arise from or be associated with thyroiditis, such as hyperthyroidism, hypothyroidism, and complications of their treatments ¹,².

• Antithyroid Drugs (Carbimazole, Propylthiouracil):
  • Before starting treatment, a full blood count (FBC) including white cell count and differential, and liver function tests (LFTs) should be checked ¹,².
  • Thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) should be measured every 6 weeks until TSH is within the reference range ¹,².
  • Subsequently, TSH (with cascading to check FT4 and FT3) should be measured every 3 months until antithyroid drugs are stopped ¹,².
  • Do not routinely monitor FBC and LFTs unless there is a clinical suspicion of agranulocytosis or liver damage ¹,².
  • After stopping antithyroid drugs, TSH (with cascading) should be checked within 8 weeks, then every 3 months for a year, and then once a year ¹,².
• Radioactive Iodine Treatment:
  • TSH, FT4, and FT3 levels should be measured every 6 weeks for the first 6 months after treatment until TSH is within the reference range ¹,².
  • If the person remains biochemically euthyroid at 6 months, consider measuring TSH (with cascading) at 9 and 12 months after treatment ¹,².
  • If euthyroid at 12 months, consider measuring TSH (with cascading) every 6 months unless hypothyroidism develops ¹,².
  • Specialist follow-up is needed as levothyroxine (LT4) replacement therapy may be required if hypothyroidism occurs ¹.
• Thyroid Surgery (Total Thyroidectomy):
  • Levothyroxine (LT4) replacement therapy will be started post-operatively, and monitoring for hypothyroidism should follow relevant guidelines ¹,².
• Thyroid Surgery (Hemithyroidectomy):
  • TSH may be measured (with cascading) annually, depending on specialist advice ¹,².
• Untreated Subclinical Hyperthyroidism:
  • Consider measuring TSH every 6 months ¹,².
  • If TSH is outside the reference range, consider measuring FT4 and FT3 in the same sample ¹,².
  • Consider stopping TSH monitoring if the TSH level stabilises (2 similar measurements within the reference range 3 to 6 months apart) ¹,².

• Untreated Subclinical Hypothyroidism:
  • For adults with a TSH above the reference range but lower than 10 mlU/litre on two separate occasions 3 months apart, and symptoms of hypothyroidism, a 6-month trial of levothyroxine may be considered ².
  • If symptoms do not improve or persist when serum TSH is within the reference range, consider stopping levothyroxine and monitor untreated subclinical hypothyroidism ².
• Levothyroxine (LT4) Therapy:
  • Once the TSH level is stable (2 similar measurements within the reference range 3 months apart), check TSH annually ³.
  • If TFTs remain abnormal or symptoms persist despite adequate LT4 doses, assess for non-compliance, drug interactions, gastrointestinal malabsorption, or simultaneous intake with interfering foods/drinks ³.

• Educate patients about important drug adverse effects and symptoms, and the need to stop the offending drug immediately if suspected ¹.
• If agranulocytosis is suspected, stop and do not restart any antithyroid drugs, and consider referral to a specialist ¹,².
• Hepatotoxicity usually develops within 3 months of starting propylthiouracil ¹.