Question: Which ICD-9 code should I report for "decreased TSH"? Can I assign a hyperthyroidism code, or is that jumping the gun? What about an ICD-9 code for an abnormal lab value?
Pennsylvania Subscriber
Answer: Low levels of thyroid stimulating hormone (TSH) will usually imply hyperthyroidism (242.9x). So if you assign hyperthyroidism, you'd probably be right 99 percent of the time. However, a coder should never make assumptions or risk labeling a patient with a condition he does not have.
The pituitary gland produces TSH, which stimulates the thyroid gland to produce thyroid hormones. A low TSH level usually means the thyroid gland is over-producing thyroid hormones, so the pituitary gland doesn't need to stimulate the gland and has reduced its production of TSH - hence the likelihood that the patient has hyperthyroidism. However, the physician will need to check the patient's thyroid hormone levels to see if they're abnormally high before making this diagnosis. A physician can never tell for sure without reading the lab results of a thyroid hormones test.
There's a chance that a low TSH could mean a pituitary problem, such as a pituitary tumor that's inhibiting TSH production. In this case, the thyroid would have nothing to do with the patient's condition. The ICD-9 manual lists 259.9 as the correct code for abnormal hormone lab findings. Therefore, you should report 259.9 (Unspecified endocrine disorder) until the physician makes a definitive diagnosis.
