ICD-10 Coding for TSH Testing in a Patient with Numb Hands
Use R20.2 (Paresthesia of skin) as the primary diagnosis code when ordering TSH for a patient presenting with numbness of the hands, as this accurately captures the presenting symptom that justifies the laboratory investigation.
Rationale for Code Selection
The appropriate ICD-10 code must reflect the presenting symptom that prompts the diagnostic workup, not the test being ordered or a suspected diagnosis. For numb hands, the correct approach is:
Primary Diagnosis Code
- R20.2 - Paresthesia of skin is the most accurate code for numbness/tingling in the hands when no underlying diagnosis has been confirmed
- This symptom-based code justifies ordering TSH as part of the differential diagnosis workup
Clinical Context for TSH Testing
Thyroid dysfunction is a recognized cause of peripheral neurological symptoms. The ACC/AHA guidelines identify specific presentations where TSH screening is indicated 1:
For Hypothyroidism:
- Clinical indications include delayed ankle reflexes, coarse skin, cold skin, and slow movement 1
- TSH and free thyroxine are the recommended screening tests 1
- Hypothyroidism prevalence is <1% but can present with neurological symptoms 1
For Hyperthyroidism:
- Can present with fine tremor of outstretched hands, warm moist skin, and nervousness 1
- TSH and free thyroxine serve as screening tests 1
The American Heart Association recommends measuring TSH to exclude thyroid dysfunction when evaluating metabolic abnormalities 2. The ACC/AHA heart failure guidelines also include TSH in initial laboratory evaluation alongside complete blood count, electrolytes, and other metabolic parameters 1.
Alternative Coding Considerations
If additional clinical context is present, consider these supplementary codes:
- E03.9 - Hypothyroidism, unspecified (only if hypothyroidism is already suspected based on other clinical findings)
- G62.9 - Polyneuropathy, unspecified (if bilateral hand numbness suggests peripheral neuropathy)
- M79.3 - Panniculitis, unspecified (if there are additional musculoskeletal symptoms)
Common Coding Pitfalls to Avoid
- Do not use E03.9 or E05.9 (thyroid disorder codes) as the primary diagnosis when ordering TSH - these imply a confirmed diagnosis rather than a diagnostic workup
- Do not use Z13.29 (encounter for screening for other suspected endocrine disorder) - this is for asymptomatic screening, not symptomatic evaluation 1
- Avoid vague codes like R53.81 (other malaise) when a more specific symptom code exists
The U.S. Preventive Services Task Force notes that TSH is the primary screening test for thyroid dysfunction, with follow-up T4 testing to differentiate subclinical from overt dysfunction 1. However, for billing and documentation purposes, the presenting symptom (R20.2) remains the appropriate primary code.