C-peptide test cost in St. Louis, MO
In St. Louis, MO-IL, 12 hospitals list a cash price for C-peptide blood test: from $55.90 to $539.06, with a median of $109.71. The lowest listed price is at Mercy Hospital South and 1 other hospital — $53.81 less than the median here. Across Missouri, the median is $105.75 at 61 hospitals.
Cash prices at 12 facilities across 10 cities for code 84681, as an outpatient — the setting a self-pay patient normally buys. Collected Sep 27, 2026; the hospital files themselves were last updated between Feb 6, 2026 and Feb 9, 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 St. Louis, MO-IL.
Hospitals, cheapest first
| Hospital | Cash price | List price | Insurers pay | Off list |
|---|---|---|---|---|
| Mercy Hospital South lowest Saint Louis, MO · (314) 525-1000 C Peptide source file | $55.90 | $86.00 | $18.73–$46.82 | 35% |
| Mercy Hospital St Louis lowest Saint Louis, MO · (314) 251-6000 C Peptide source file | $55.90 | $86.00 | $5.59–$86.00 | 35% |
| Carlinville Area Hospital Carlinville, IL · (217) 854-3141 C-PEPTID source file | $63.00 | $90.00 | $32.40–$128.57 | 30% |
| Mercy Hospital Washington Washington, MO · (636) 239-8000 C Peptide source file | $84.50 | $130.00 | $8.45–$117.00 | 35% |
| Community Hospital of Staunton Staunton, IL · (618) 635-2200 C PEPTIDE File of Feb 9, 2026 · source file | $103.45 | $206.90 | $59.82–$188.28 | 50% |
| Mercy Hospital Jefferson Festus, MO · (636) 933-1000 C Peptide source file | $105.95 | $163.00 | $10.60–$163.00 | 35% |
| Touchette Regional Hospital Cahokia Heights, IL · (618) 332-3060 C-peptide source file | $113.46 | $183.00 | $6.96–$174.00 | 38% |
| Hshs Holy Family Hospital Greenville, IL · (618) 664-1230 HC C PEPTIDE-90 source file | $130.32 | $181.00 | $8.82–$181.00 | 28% |
| Anderson Hospital Maryville, IL · (618) 288-5711 C PEPTIDE File of Feb 6, 2026 · source file | $133.40 | $266.80 | $19.46–$240.12 | 50% |
| Shriners Childrens - St Louis Saint Louis, MO · (314) 432-3600 ASSAY OF C-PEPTIDE source file | $134.50 | $134.50 | $10.15–$35.76 | — |
| Carlinville Area Hospital Carlinville, IL · (217) 854-3141 C-PEPTIDE 24 HR URINE(REF) source file | $136.50 | $195.00 | $70.20–$278.57 | 30% |
| Mercy Hospital Lincoln Troy, MO · (636) 528-8551 C Peptide source file | $143.65 | $221.00 | $20.81–$29.47 | 35% |
| Carlinville Area Hospital Carlinville, IL · (217) 854-3141 C-PEPTIDE(REF) source file | $188.30 | $269.00 | $96.84–$384.29 | 30% |
| Gateway Regional Medical Center Granite City, IL · (618) 798-3000 Q372 C-PEPTIDE IA+1 more line at this price source file | $539.06 | $898.44 | $898.44 | 40% |
Outpatient: lowest $55.90, median $109.71, highest $539.06 — a 9.6× difference within the same market.
As an inpatient, the same code is billed by 7 facilities here, median $130.32. Inpatient and outpatient prices are not comparable and are kept on separate pages: the inpatient charge covers admission, not the same purchase.
Cash or insurance?
At 9 of 12 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 C-peptide test shows how much insulin the pancreas is making. It helps tell type 1 from type 2 diabetes and find the cause of low blood sugar.
What the price covers
The price usually covers running the test. The blood draw (36415) is often billed as a separate line.