Adverse effect of thyroid hormones and substitutes, sequela

This code signifies a long-term or residual condition resulting from a past adverse reaction to thyroid hormones or their synthetic substitutes. It indicates that the patient is experiencing a lasting health problem directly attributable to a previous unwanted effect of these medications, rather than an acute or current adverse event.

Apply this code when documenting a chronic or permanent complication that developed as a consequence of an adverse effect from thyroid hormone therapy. Examples include persistent cardiac arrhythmias, bone density issues, or neurological deficits that are directly linked to a prior episode of thyroid hormone toxicity. This code is appropriate when the acute adverse event has resolved, but its lasting impact remains.

• Always use this code as a secondary diagnosis, following the code for the specific sequela (e.g., I47.1 for paroxysmal supraventricular tachycardia).
• Ensure documentation clearly links the current chronic condition to a past adverse effect of thyroid hormones.
• Do not use for acute or current adverse effects; those require codes from the T38.1X1-T38.1X4 series.