Category: Thyroid

Monitor: 17


Thursday, Apr 25
12:30 PM – 1:00 PM

Objective :

This is a case presentation of a 61-year-old female referred to endocrinology due to difficulty controlling post-ablative hypothyroidism secondary to Grave’s disease. Treatment of Grave’s disease can include thionamides, radioablation, and surgery. After radioiodine ablation, thyroid function tests are performed every 4-6 weeks and can be spread out to every 6-12 months once patient becomes euthyroid. But what if that never happens? Correlating a patient’s symptoms with their lab values and coming up with a treatment plan can be as much of an art as it is a science. Human anti-mouse antibodies interfere with immunoassays which lead to falsely increased or falsely depressed measurements of thyroid hormones.

Methods : N/A

Results : N/A

Discussion :

A 61-year-old female with post-ablative hypothyroidism due to a previous history of Graves’ disease was treated with radioactive iodine at the age of 40. Since ablation she was on replacement doses ranging from 75mcg-185mcg of thyroxine with atypical fluctuations in her TSH. She was referred to endocrinology with complaints of weight loss, fatigue, decreased appetite, chest pain, palpitations, shortness of breath, anxiety and mood swings. Additional medical history included paroxysmal supraventricular tachycardia for which patient underwent radiofrequency ablation, Takotsubo syndrome, and hypertension. Her TSH on referral was 11.79 µIU/mL (Ref 0.35 - 5.5 µIU/mL) with free T4 of 1.18 ng/dL (Ref 0.9 - 1.8 ng/dL). Two months earlier her TSH was 0.39 µIU/mL. It was felt her fluctuations may be due to taking the generic form of the medication, and ingesting it with coffee. She was switched to the brand name formulation and advised on taking the medication with water. On her next check 6 weeks later her TSH improved to 2.16 µIU/mL, only to rise again to 5.08 µIU/mL the following visit. Eventually, due to continued fluctuations in TSH in spite of multiple dose adjustments and persistent symptoms, it was decided to check for human anti-mouse antibodies (HAMA). Their significant presence was confirmed. As a result, the patient’s dosing was titrated based on free T4 and T3 levels with symptomatic improvement.

Conclusion :

Human anti-mouse antibodies (HAMA) are a relatively common type of human anti-animal immunoglobulins that have been previously described as interfering with lab immunoassays. They can be found in as many as 10% of patients. These heterophile antibodies may be induced by therapies with murine monoclonal antibodies and vaccines containing animal immunoglobulins. As clinicians increasingly rely on lab assays to guide therapy, it is important to be aware of potential interfering mechanisms.


Ilia Bernstein

Resident Physician
Jewish Hospital of Cincinnati

Jewish Hospital Resident Physician in Internal Medicine

Emily C. Silverman

Resident Physician
Jewish Hospital of Cincinnati
Blue Ash, Ohio

Internal Medicine resident physician at Jewish Hospital of Cincinnati

Omar Akhtar

Jewish Hospital/Mercy Health
Mason, Ohio

Dr. Omar Akhtar is a board certified Endocrinologist. He completed his fellowship in Endocrinology from Marshall University.