Lab tests CPT 84100 Inpatient — admitted to hospital

Phosphorus test cost in San Luis Obispo, CA — inpatient

In San Luis Obispo-Paso Robles, CA, 1 hospital lists a cash price for phosphorus (phosphate) blood test as an inpatient: from $9.34 to $9.34, with a median of $9.34. Across California, the median is $75.60 at 198 hospitals.

Cash prices at 1 facility for code 84100, as an inpatient (admitted to hospital) . Collected Sep 27, 2026; the hospital files themselves were last updated between Feb 28, 2026 and Feb 28, 2026.

Lowest$9.34French Hospital Medical Center

Median$9.34half of hospitals charge less

Highest$9.34in this market

Difference1.0×highest vs lowest

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 Luis Obispo-Paso Robles, CA.

median

Lowest $9.34Highest $101.92

Hospitals, cheapest first

Hospital	Cash price	List price	Insurers pay	Off list
French Hospital Medical Center lowest San Luis Obispo, CA · (805) 543-5353 RL-A-MAYO- RTRP2C File of Feb 28, 2026 · source file	$9.34	$23.82	$6.44–$23.35	61%
French Hospital Medical Center San Luis Obispo, CA · (805) 543-5353 RL-A-NMS CATH ST 1033ST B File of Feb 28, 2026 · source file	$48.61	$124.00	$33.48–$121.52	61%
French Hospital Medical Center San Luis Obispo, CA · (805) 543-5353 PHOSPHORUS File of Feb 28, 2026 · source file	$101.92	$260.00	$70.20–$254.80	61%

Hospital The hospital that published the price, its city and the line exactly as written in its price file.

Cash price The hospital's own price for a patient paying without insurance (“discounted cash” in its price file). Hospitals must publish it under federal law, 45 CFR 180.50. Call to confirm it before booking. More

List price The hospital's full chargemaster price (“gross charge”) before any discount. Almost nobody pays it; the gap to the cash price shows what the self-pay discount is worth. More

Insurers pay The lowest and highest rates this hospital has agreed with insurance plans for the same item, from its price file. If the cash price is below what your plan pays and you have not met your deductible, paying cash can cost you less. More

Off list How much lower the cash price is than the list price.

Check the item The description in the hospital file looks like a supply or device (a catheter, a brace, an implant), not this procedure. The hospital may have filed it under the wrong code: ask before relying on this price.

Inpatient: lowest $9.34, median $9.34, highest $9.34.

As an outpatient, the same code is billed by 1 facility here, median $5.10 — that is the price to compare if you are not being admitted.

Cash or insurance?

At the one hospital here that publishes insurer rates for this code, the cash price is below the highest rate a health plan has negotiated. 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 phosphorus test measures phosphate in the blood. It is used with calcium for kidney disease, bone disease and parathyroid problems.

What the price covers

The price usually covers running the test. The blood draw (36415) is often billed as a separate line.

1 row held back from this comparison

It is priced below $1 or below a tenth of the national median for code 84100 ($42.00). 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.

Hospital	Cash price	File
French Hospital Medical Center San Luis Obispo, CARL-A-PHOS 20028	$2.54	file

File Link to the hospital's own price file.