CMS Price Transparency Data

Blood test, magnesium

Facility: UCSF Health St. Mary's Hospital

Billing Code: 83735 (CPT)

The BaseRate · fair price high confidence

A fair price for this

about 1.1× the $7 Medicare rate · typically $7–$14

modeled estimate · not a bill or quote

What this hospital charges insurers

$13

Above the fair price

about $5 over the fair price · 1.9× Medicare

Medicare pays $7 Fair price $8 This hospital $13 Cash price $24 Hospital's list price $24

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 $13

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

A fair price for a Blood test, magnesium is about $8 (about 1.1× the $7 Medicare rate). UCSF Health St. Mary's Hospital charges insurers about $13, or about $24 in cash — above the fair price. Located in San Francisco, CA.

This price is above the fair BaseRate — you may be able to pay less

Ask the hospital for the cash / self-pay price, check whether you qualify for financial assistance, or negotiate the bill down toward the fair price of about $8. Many patients pay well below the first number they’re quoted — the checklists below walk you through it.

What each insurance company pays

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

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

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

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	$7 - $8	104%
Blue Cross Blue Shieldmajor	$6 - $174	90%
Aetnamajor	$7 - $38	104%
Cignamajor	$29 - $31	433%
Humanamajor	$7	104%
Kaiser Permanentemajor	$7 - $163	104%
Health Net	$7 - $13	104%
Oscar Health	$22	328%
+ 9 smaller / regional plans	$5 - $253

Excludes 2 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 24), 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 UCSF Health St. Mary's Hospital 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 UCSF Health St. Mary's Hospital

Compare: Blood test, magnesium at other CA hospitals

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