CMS Price Transparency Data

Blood test, magnesium

Facility: Marinhealth Medical Center

Billing Code: 83735 (CPT)

The BaseRate · fair price high confidence

A fair price for this

$10

about 1.4× the $7 Medicare rate · typically $7–$15

modeled estimate · not a bill or quote

What this hospital charges insurers

Below the fair price — a good deal

about $2 under the fair price · 1.1× Medicare

Medicare pays $7 Fair price $10 This hospital $8 Cash price $81 Hospital's list price $135

How we calculate the fair BaseRate →

How this hospital compares to other CA hospitals

Highest price of the 9 CA hospitals we have prices for — worth calling around.

Cheapest $6 Priciest $8

Black dot = this hospital, among the 9 CA hospitals with a price for this procedure. Full list below.

⚠ The cash price looks unusually high next to the insurance price — it may be the full list price, not a real cash discount. Call to confirm the self-pay rate.

A fair price for a Blood test, magnesium is about $10 (about 1.4× the $7 Medicare rate). Marinhealth Medical Center charges insurers about $8, or about $81 in cash — below the fair price — a good deal. Located in Greenbrae, CA.

What each insurance company pays

Which insurers have negotiated a price with this hospital for this procedure — and which haven’t.

5 of 6 major insurers have a published price at this hospital

✓ UnitedHealthcare✓ Blue Cross Blue Shield✓ Aetna✓ Cigna✓ Kaiser Permanente Humana

Crossed out = this hospital hasn’t published a negotiated price for that insurer for this procedure. It doesn’t necessarily mean they aren’t accepted — ask your insurer.

Insurance company	Price range	vs. Medicare
UnitedHealthcaremajor	$4 - $2,330	60%
Blue Cross Blue Shieldmajor	$4 - $46	60%
Aetnamajor	$4 - $14	60%
Cignamajor	$4 - $20	60%
Kaiser Permanentemajor	$7	104%
Health Net	$7 - $17	104%
+ 7 smaller / regional plans	$7 - $42

Excludes 4 rental-network / third-party entries (e.g. Multiplan, PHCS) — these are pricing networks, not insurers.

Self-Pay How to get the cash price

Tell the billing desk you want to be billed as self-pay — not through insurance — before your visit.
Ask for the cash / prompt-pay discount in writing, with the exact price (about 81), before you agree to anything.
Get it in writing that they won’t also bill your insurance, so the cash price is what you owe.
Check the CPT code on your bill matches exactly: 83735.

Insurance Before you use insurance

Call your insurance company to confirm Marinhealth Medical Center is in-network.
Ask your insurer whether prior approval is required for CPT code 83735.
Confirm the doctor or provider is in-network too — not just the hospital building.
Check your Explanation of Benefits against the hospital’s final itemized bill.

Estimate your out-of-pocket cost

A rough estimate of what you’d pay with insurance (deductible + coinsurance) versus paying the cash price yourself.

How you’d pay

Deductible left to meet ($)

Your coinsurance (%)

Enter your details and press estimate to compare.

Other Procedures at Marinhealth Medical Center

Compare: Blood test, magnesium at other CA hospitals

Insurance negotiated median for the same procedure, sorted lowest first.