Hyperthyroidism ICD-10-CM codes

Category E05 (thyrotoxicosis) is organized by cause in the fourth character: E05.0- thyrotoxicosis with diffuse goiter (Graves disease), E05.1- toxic single thyroid nodule, E05.2- toxic multinodular goiter, E05.3- ectopic thyroid tissue, E05.4- thyrotoxicosis factitia (excess exogenous thyroid hormone), E05.8- other thyrotoxicosis, and E05.9- unspecified. The fifth character is always required: 0 without thyrotoxic crisis or storm, 1 with thyrotoxic crisis or storm. E05.90 is the code for hyperthyroidism documented without a cause; Graves disease is E05.00.

Thyroid storm is a life-threatening emergency and is coded with the fifth character 1 (for example E05.01 for Graves disease with storm). The terms hyperthyroidism and thyrotoxicosis both index to E05. Subclinical hyperthyroidism with a suppressed TSH and normal free T4 is coded E05.90 only when the provider documents it as a diagnosis; an abnormal thyroid function result without a diagnosis is R94.6.

Transient thyrotoxicosis from thyroiditis is coded to the thyroiditis: E06.1 subacute (de Quervain) thyroiditis or E06.3 autoimmune (Hashimoto) thyroiditis, rather than E05. E07.81 (sick-euthyroid syndrome) is for abnormal thyroid tests in a systemically ill patient with a normal thyroid. Hypothyroidism that follows radioactive iodine ablation or thyroidectomy for hyperthyroidism is E89.0 (postprocedural hypothyroidism). Long-term methimazole or propylthiouracil therapy can be reported with Z79.899.