Magnesium test cost in San Francisco, CA — inpatient
In San Francisco-Oakland-Fremont, CA, 11 hospitals list a cash price for magnesium blood test as an inpatient: from $64.58 to $254.80, with a median of $120.40. The lowest listed price is at Hayward Sisters Hospital — $55.82 less than the median here. Across California, the median is $106.08 at 103 hospitals.
Cash prices at 11 facilities across 11 cities for code 83735, as an inpatient (admitted to hospital) . Collected Sep 23, 2026; the hospital files themselves were last updated between Feb 23, 2026 and Apr 1, 2026.
Where each hospital's price falls
Each dot is one hospital's cash price on a scale from the lowest to the highest in San Francisco-Oakland-Fremont, CA.
Hospitals, cheapest first
| Hospital | Cash price | List price | Insurers pay | Off list | File date |
|---|---|---|---|---|---|
| Hayward Sisters Hospital lowest Hayward, CA · (510) 782-6200 MAGNESIUM | $64.58 | $215.25 | $150.68–$165.74 | 70% | Feb 23, 2026 source file |
| Kaiser Foundation Hospital - San Francisco San Francisco, CA · (415) 833-2646 ASSAY OF MAGNESIUM | $120.40 | $215.00 | $6.00–$20.00 | 44% | — source file |
| Kaiser Foundation Hospital - Oakland/Richmond Oakland, CA · (510) 752-1000 ASSAY OF MAGNESIUM | $120.40 | $215.00 | $6.00–$20.00 | 44% | — source file |
| Kaiser Foundation Hospital - Walnut Creek Walnut Creek, CA · (925) 295-4000 ASSAY OF MAGNESIUM | $120.40 | $215.00 | $6.00–$20.00 | 44% | — source file |
| Kaiser Foundation Hospital - Fremont Fremont, CA · (510) 784-4000 ASSAY OF MAGNESIUM | $120.40 | $215.00 | $6.00–$20.00 | 44% | — source file |
| Kaiser Foundation Hospital - Redwood City Redwood City, CA · (650) 299-2000 ASSAY OF MAGNESIUM | $120.40 | $215.00 | $6.00–$20.00 | 44% | — source file |
| Kaiser Foundation Hospital - San Rafael San Rafael, CA · (415) 444-2000 ASSAY OF MAGNESIUM | $120.40 | $215.00 | $6.00–$20.00 | 44% | — source file |
| Kaiser Foundation Hospital - Antioch Antioch, CA · (925) 813-6500 ASSAY OF MAGNESIUM | $120.40 | $215.00 | $6.00–$20.00 | 44% | — source file |
| Kaiser Foundation Hospital - San Leandro San Leandro, CA · (510) 454-1000 ASSAY OF MAGNESIUM | $120.40 | $215.00 | $6.00–$20.00 | 44% | — source file |
| Kaiser Foundation Hospital - South San Francisco South San Francisco, CA · (650) 742-3200 ASSAY OF MAGNESIUM | $120.40 | $215.00 | $6.00–$20.00 | 44% | — source file |
| Stanford Health Care Tri-Valley Pleasanton, CA · (925) 847-3000 HC Magnesium Serum/Pl | $254.80 | $637.00 | — | 60% | Apr 1, 2026 source file |
Inpatient: lowest $64.58, median $120.40, highest $254.80 — a 3.9× difference within the same market.
As an outpatient, the same code is billed by 12 facilities here, median $120.40 — that is the price to compare if you are not being admitted.
Cash or insurance?
At 1 of 10 hospitals that publish insurer rates for this code here, the cash price is below the highest rate a health plan has negotiated, and at 1 it is below every plan's rate. If you have insurance but have not met your deductible, you usually pay your plan's negotiated rate, which falls somewhere in the "Insurers pay" column. Paying cash can cost less, but a cash payment usually does not count toward your deductible. Ask the hospital for both numbers before you book.
What it is
A magnesium test measures the level of magnesium in the blood. Doctors order it for muscle cramps or weakness, an irregular heartbeat, low potassium or calcium that does not correct, and for people on diuretics, long-term acid-reducing drugs or with kidney disease.
What the price covers
The price usually covers running the test. The blood draw (36415) is often billed as a separate line.
2 rows held back from this comparison
They are priced below $1 or below a tenth of the national median for code 83735 ($43.50). Such a line is almost always a physician's fee billed separately, an assistant's share or a placeholder — a real charge, but not the price of the procedure itself.
| Hayward Sisters Hospital Hayward, CALC- magnesium24hrurine | $1.79 | file |
| Hayward Sisters Hospital Hayward, CALC -MAGNESIUMURINE | $1.79 | file |