CPT Code 83735 — What It Means and What Medicare Pays

CPT code · Lab test · Typically billed in: Lab

What CPT code 83735 means: A magnesium blood test.

Seeing CPT code 83735 on your medical bill?
This code is only one part of the picture — your bill, EOB, insurance adjustments, units, and other charges may affect what you actually owe. MD Bill Check reads the codes on your document, checks the bill in context, and flags items that may be worth reviewing.

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What Medicare pays for CPT code 83735

What CPT code 83735 costs: Medicare's 2025 national average payment for CPT code 83735 is $6.70.

Medicare national average (2025): $6.70 (Clinical Laboratory Fee Schedule)

Treat this as a reference point, not a ceiling. It is what Medicare pays nationally before any local adjustment — private insurers negotiate their own rates, and a hospital's list price for the same code is often several times higher. A charge far above this number is not automatically an error, but it is a fair thing to ask about.

How many units of CPT code 83735 should appear on one day

Units normally expected per day: Medicare normally expects at most 4 units of CPT code 83735 per patient per day. More than 4 units a day is clinically unlikely rather than impossible, so a higher count is usually reviewed by hand rather than denied outright.

If your bill shows more units of CPT code 83735 for a single date of service than that, it is worth asking the billing office to explain the count — duplicate lines and unit-entry mistakes are among the most common medical-billing errors.

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Frequently asked questions about CPT code 83735

What does CPT code 83735 mean on a medical bill?

A magnesium blood test. Bills group it under "Lab test", and it is typically provided in this setting: Lab.

How much does CPT code 83735 cost?

Medicare's 2025 Clinical Laboratory Fee Schedule pays a national rate of $6.70 for CPT code 83735. That figure is a public Medicare benchmark, not a cap on what a provider may charge you — commercial insurers negotiate their own rates and hospital list prices are often several times higher.

How many units of CPT code 83735 can be billed per day?

Medicare's Medically Unlikely Edits normally expect at most 4 units of CPT code 83735 per patient per day. More than 4 units a day is clinically unlikely rather than impossible, so a higher count is usually reviewed by hand rather than denied outright.

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