Magnesium test cost in St. Louis, MO
In St. Louis, MO-IL, 12 hospitals list a cash price for Magnesium blood test: from $7.92 to $114.48, with a median of $56.58. The lowest listed price is at Ranken Jordan Home for Convalescent Crippled Children Hospital — $48.66 less than the median here. Across Missouri, the median is $36.63 at 30 hospitals.
Cash prices at 12 facilities across 10 cities for code 83735, as an outpatient — the setting a self-pay patient normally buys. Collected Sep 23, 2026; the hospital files themselves were last updated between Apr 24, 2026 and Apr 24, 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 | File date |
|---|---|---|---|---|---|
| Ranken Jordan Home for Convalescent Crippled Children Hospital lowest Maryland Heights, MO Magnesium Level | $7.92 | $9.90 | — | 20% | Apr 24, 2026 source file |
| Ranken Jordan Home for Convalescent Crippled Children Hospital Maryland Heights, MO Magnesium, 24 Hour Urine | $20.15 | $25.18 | — | 20% | Apr 24, 2026 source file |
| Mercy Hospitals East Communities dba Mercy Hospital St Louis Saint Louis, MO Magnesium | $24.05 | $37.00 | $2.41–$37.00 | 35% | — source file |
| Mercy Hospital Jefferson Festus, MO Magnesium | $24.05 | $37.00 | $2.41–$37.00 | 35% | — source file |
| Mercy Hospital South Saint Louis, MO Magnesium RBC | $29.25 | $45.00 | $6.03–$15.08 | 35% | — source file |
| American Healthcare Systems Illinois LLC Granite City, IL L910235 MAGNESIUM, URINE | $40.20 | $67.00 | $67.00 | 40% | — source file |
| Mercy Hospital South Saint Louis, MO Magnesium Urine | $52.00 | $80.00 | $6.03–$15.08 | 35% | — source file |
| Shriners Childrens - St Louis Saint Louis, MO ASSAY OF MAGNESIUM | $52.70 | $52.70 | $2.81–$11.51 | — | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital St Louis Saint Louis, MO Magnesium Urine | $60.45 | $93.00 | $6.05–$93.00 | 35% | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital Washington Washington, MO Magnesium Urine | $60.45 | $93.00 | $6.05–$83.70 | 35% | — source file |
| Mercy Hospital Jefferson Festus, MO Magnesium Urine | $60.45 | $93.00 | $6.05–$93.00 | 35% | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital Washington Washington, MO Magnesium | $62.40 | $96.00 | $6.03–$11.33 | 35% | — source file |
| Mercy Hospital Jefferson Festus, MO Stone Risk Ua Magnesium | $70.20 | $108.00 | $7.02–$108.00 | 35% | — source file |
| Mercy Hospital Jefferson Festus, MO Magnesium Stool | $70.20 | $108.00 | $6.03–$15.08 | 35% | — source file |
| Mercy Hospital Jefferson Festus, MO Magnesium 24 Hr Urine | $70.20 | $108.00 | $6.03–$15.08 | 35% | — source file |
| Mercy Hospital Jefferson Festus, MO Magnesium RBC | $70.20 | $108.00 | $6.03–$15.08 | 35% | — source file |
| Mercy Hospital South Saint Louis, MO Magnesium Stool | $74.75 | $115.00 | $6.03–$15.08 | 35% | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital St Louis Saint Louis, MO Magnesium 24 Hr Urine | $76.05 | $117.00 | $6.03–$15.08 | 35% | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital St Louis Saint Louis, MO Stone Risk Ua Magnesium | $76.05 | $117.00 | $7.61–$117.00 | 35% | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital St Louis Saint Louis, MO Magnesium Stool | $76.05 | $117.00 | $6.03–$15.08 | 35% | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital St Louis Saint Louis, MO Magnesium RBC | $76.05 | $117.00 | $6.03–$15.08 | 35% | — source file |
| Mercy Hospital Lincoln Troy, MO Magnesium 24 Hr Urine | $76.70 | $118.00 | $5.93–$15.08 | 35% | — source file |
| Mercy Hospital South Saint Louis, MO Magnesium 24 Hr Urine | $78.00 | $120.00 | $6.03–$15.08 | 35% | — source file |
| Mercy Hospital South Saint Louis, MO Magnesium | $78.65 | $121.00 | $7.87–$121.00 | 35% | — source file |
| Mercy Hospital Lincoln Troy, MO Stone Risk Ua Magnesium | $78.65 | $121.00 | $7.87–$121.00 | 35% | — source file |
| Mercy Hospital Lincoln Troy, MO Magnesium Urine | $79.30 | $122.00 | $5.93–$15.08 | 35% | — source file |
| Mercy Hospital Lincoln Troy, MO Magnesium | $79.30 | $122.00 | $5.93–$15.08 | 35% | — source file |
| St Josephs Hospital Hospital Sisters Third Order of St Francis Breese, IL ASSAY OF MAGNESIUM | $79.92 | $111.00 | $3.80–$111.00 | 28% | — source file |
| Mercy Hospital Lincoln Troy, MO Magnesium RBC | $79.95 | $123.00 | $5.93–$15.08 | 35% | — source file |
| Mercy Hospital South Saint Louis, MO Stone Risk Ua Magnesium | $83.20 | $128.00 | $8.32–$128.00 | 35% | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital Washington Washington, MO Magnesium Stool | $83.85 | $129.00 | $8.39–$116.10 | 35% | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital Washington Washington, MO Magnesium 24 Hr Urine | $83.85 | $129.00 | $6.03–$11.33 | 35% | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital Washington Washington, MO Magnesium RBC | $83.85 | $129.00 | $6.03–$11.33 | 35% | — source file |
| Mercy Hospitals East Communities dba Mercy Hospital Washington Washington, MO Stone Risk Ua Magnesium | $83.85 | $129.00 | $8.39–$116.10 | 35% | — source file |
| Mercy Hospital Lincoln Troy, MO Magnesium Stool | $84.50 | $130.00 | $8.45–$130.00 | 35% | — source file |
| St Josephs Hospital of the Hospital Sisters of the Third Order of St Francis Highland, IL ASSAY OF MAGNESIUM | $102.24 | $142.00 | $8.84–$142.00 | 28% | — source file |
| St Elizabeths Hospital of the Hospital Sisters of the Third Order of St Francis O'Fallon, IL HC MAGNESIUM | $105.12 | $146.00 | $3.80–$146.00 | 28% | — source file |
| Hshs Holy Family Hospital Inc Greenville, IL ASSAY OF MAGNESIUM | $114.48 | $159.00 | $3.99–$159.00 | 28% | — source file |
| American Healthcare Systems Illinois LLC Granite City, IL Q442 MAGNESIUM | $206.46 | $344.10 | $344.10 | 40% | — source file |
Outpatient: lowest $7.92, median $56.58, highest $114.48 — a 14.5× difference within the same market.
As an inpatient, the same code is billed by 8 facilities here, median $91.08. 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 8 of 11 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.