Can Hypothyroidism Affect HIV Results?
Thyroid
Detailed Answer:
Hypothyroidism is not known to affect results of HIV testing.
Regarding the cause of your hypothyroid condition, the most common cause worldwide is 'Hashimoto's thyroiditis'. As you have correctly surmised, it is an auto immune problem ie the body's own defenses target the thyroid cells and eventually tend to make the gland under-active over time, typically necessitating lifelong treatment with levothyroxine.
The most useful test to ascertain if your hypothyroidism is due to Hashimoto's, is a blood check for anti-TPO (Thyroid Peroxidase) and anti-Thyroglobulin antibodies.
Either or both of these auto-antibodies are usually positive in Hashimoto's induced hypothyroidism.
However, these are not known to impact the HIV test results.