Mark Sarnak, MD
Nephrology · Boston, MANPI 1982641502
Payments from drug & device makers
What this record shows
This record is dominated by consulting fees: $33,280 of the $35,731 with a category attached, or 93.1%. 8 manufacturers reported payments, led by Akebia Therapeutics Inc at 36.3% of the total. Reporting peaked in 2023 at $11,806 and has fallen 50.5% since, to $5,838 in 2025. Among nephrology clinicians in MA with any reported payments, this total sits in the top 10% — high for the specialty, which is a reason to read the composition above rather than the number alone.
Across 61 payments — averaging $585.76 each. Meals, travel, consulting and speaking fees, gifts and royalties reported by drug and device makers.
- Akebia Therapeutics Inc$13K
- Boehringer Ingelheim$9K
- Astrazeneca UK Limited$7K
- Bayer$5K
- AstraZeneca$2K
- Fresenius USA Marketing, Inc.$249
- plus $82 from 2 others
What the payments were for
- Consulting fees$33,28093%
- Speaking & faculty fees$2491%
- Travel & lodging$1,0393%
- Food & beverage$1,1313%
- Education$320%
General payments by program year
Who reported the general payments
Companies are grouped under their corporate parent — a single manufacturer often files under several CMS reporting entities. Research and ownership payments are counted separately and are not in this table.
| Company | Payments | Total |
|---|---|---|
| Akebia Therapeutics Inc | 11 | $12,960 |
| Boehringer Ingelheim | 15 | $9,176 |
| Astrazeneca UK Limited | 6 | $7,000 |
| Bayer | 19 | $4,698 |
| AstraZeneca(2 entities) | 4 | $1,566 |
| Fresenius USA Marketing, Inc. | 1 | $249 |
| Corcept Therapeutics | 1 | $50 |
| Travere Therapeutics, Inc. | 4 | $32 |
What the payments were tied to
Products named in the reported payments. Only payments of $100 or more are attributed here — the typical reported payment nationally is a meal worth about $16, and listing those product-by-product would be noise.
- Vafseo$4,535
- Non-Covered$4,089
- Kerendia$235
How this compares
$35,731 in reported general payments places this provider in the 90th percentile of 339 nephrology providers in Massachusetts.
Medicare billing
What this is not: this is the amount Original Medicare Part B allowed for services this provider billed in 2024. It is not their income. It excludes Medicare Advantage — now more than half of all Medicare enrollment — along with Medicaid and all commercial insurance, and it is gross practice revenue before staff, rent, supplies and malpractice premiums. CMS also suppresses any figure covering ten or fewer patients, so low-volume providers appear smaller than they are.
Other nephrology in Boston
- David FriedmanBoston$19.8M
- Martin PollakBoston$19.8M
- Dennis AusielloBoston$4.6M
- Ajay SinghBoston$916K
- Leslie FangBoston$388K
- Jean FrancisBoston$244K
- Joseph BonventreBoston$175K
- Andrew AllegrettiBoston$139K
- Ravi ThadhaniBoston$115K
- Meghan SiseBoston$113K
Where these figures come from
- Payments: CMS Open Payments, program years 2019–2025 (publication P06302026_06032026).
- Billing: Medicare Physician & Other Practitioners, data year 2024. Original Medicare Part B only.
- Identity: NPPES NPI Registry, July 2026.