A 59-year old feminine patient presented with apathy and 6 kg

A 59-year old feminine patient presented with apathy and 6 kg weight gain. Feet3, however Feet4 concentration remained elevated (2.1 ng/ml). Following this, L-T4 was restarted. On admission to our Division, she was clinically euthyroid on L-T4, 88 g, once daily. Investigations on Roche? platform confirmed mildly elevated TSH – 5.14 (rr: 0.27-4.2 IU/ml) with high FT4 [4.59 (rr: 0.93-1.7 ng/ml)] and FT3 [4.98 (rr: 2.6-4.4 pg/ml)] concentrations. Additional tests exposed hypoechogenic ultrasound pattern standard for Hashimoto thyroiditis. There was no discrepancy in determined TSH value following TSH dilution (101% recovery). Concentrations of Feet4 and Feet3 were assessed on the day of discontinuation of L-T4 and after four days by the means of Abbott? Architect I 1000SR platform. These exposed Feet4 and Feet3 concentrations within the TG-101348 research range [e.g., Feet4 – 1.08 ng/ml (rr: 0.7-1.48)] TG-101348 4.59 ng/ml (rr: 0.93-1.7, Roche?), Feet3 – 3.70 pg/ml (rr: 1.71-3.71) 4.98 (rr: 2.6-4.4, Roche?)], confirming assay interference. Concentrations of ferritin and SHBG were normal. Conclusions Clinicians must be aware of possible assay interference, including the measurements of Feet4 and Feet3 in the differential analysis of abnormal results of thyroid function checks that do not match the patient clinical presentation. Keywords: Free T4, Free T3, Assay interference Case presentation Written informed consent was obtained from the patient for publication of this case report and any accompanying images. The publication in question was approved by the ethical committee of the Polish Mothers Memorial Hospital C Research Institute. A 59-year old female patient presented with a history of apathy and weight gain (about 5C6 kg). Initial investigations revealed severe primary hypothyroidism (TSH>100 IU/ml), moderate hyperlipidaemia (total cholesterol 239 mg/dl, triglicerides 185 mg/dl) and normal fasting glucose (83 mg/dl). She was started on L-thyroxine (L-T4), 25 g, once daily, the dose of which was gradually titrated up to 75 g, once daily, with clinical improvement. Other investigations revealed very high titre of anti-thyroid peroxidase antibodies (>4000 IU/ml (reference up to 115 IU/ml)). After about 3 months of treatment test revealed expected fall in TSH concentrations (to 12.74 IU/ml), however, with unexpectedly high free thyroxine (FT4) and free triiodotyronine (FT3) concentrations (Siemens? platform – see Table?1). At this stage L-T4 was stopped, this was followed by a rapid increase in Rabbit Polyclonal to DHRS4. TSH (to 77.76 IU/ml) and some decrease in FT4 and FT3, however, FT4 concentration still remained elevated. Following this, L-T4 was restarted. There was a gradual decrease in TSH, with FT4 and FT3 concentrations above the reference range. The patient was referred for the second opinion. Table TG-101348 1 Initial results in the 59-year old female patient before and during treatment with L-T4 On admission to our Department, she was clinically euthyroid. Her medication included L-T4, 88 g, once daily, Rosuvastatin, 10 mg, once daily, Amlodipine, 5 mg x 1, once daily, Metoprolol slow release, 25 mg, once daily. There was no overt history of angina. She did not smoke and did not consume alcoholic beverages in excess. Investigations TG-101348 performed in our Department (Roche? platform) confirmed mildly elevated TSH with high FT4 and FT3 concentrations (Table?2). The patient vehemently denied any compliance problems. Other tests confirmed very high titres of anti-thyroid peroxidase (anti-TPO) anti-thyroglobulin (anti-Tg) antibodies [anti-Tg > 4000.00 IU/ml (rr: up to 115 IU/ml); anti-TPO antibodies > 600.00 IU/ml (rr: up to 34 IU/ml)] and hypoechogenic ultrasound pattern typical for Hashimoto thyroiditis. Cortisol concentration was 10.52 g/dl, ACTH 14.7 pg/ml (rr: 0C46 pg/ml). There was no discrepancy in calculated TSH value following TSH dilution (Table?2). Following this, L-T4 was stopped with assessment of thyroid function (Table?3). Again there was a gradual increase of TSH with some decrease in FT4 and FT3, however, still above the reference ranges. We also assessed FT4 and FT3 TG-101348 on the day of discontinuation of L-T4 and after 4 days in a different laboratory (Abbott? Architect I 1000SR platform C Table?3). This revealed FT4 and FT3 concentrations within reference ranges. Furthermore, the measured FT4 concentration was about 4 times lower than for the Roche? system (Desk?3). Concentrations of.