Exhibit 10.1

Confidential portions of this Exhibit, denoted by bracketed asterisks, have been omitted and filed separately with the Securities and Exchange Commission in reliance on Rule 24b-2 of the Securities Exchange Act of 1934.

THIRD AMENDMENT TO SUPPLY AGREEMENT

This Third Amendment to Supply Agreement (“Third Amendment”) dated July 22, 2013 (“Third Amendment Effective Date”) is made by and between Laboratorios PiSA S.A. de C.V., a corporation organized under the laws of Mexico having offices at Calle 7 No. 1308 Zona Industrial, C.P. 44940 Guadalajara, Jal., Mexico (“PiSA”) and Medisystems Corporation, a Washington corporation, having offices at 350 Merrimack Street, Lawrence, Massachusetts 01843, USA (“MDS”).

BACKGROUND

WHEREAS, PiSA and NxStage Medical, Inc. (“NxStage”) entered into that certain Supply Agreement dated as of March 12, 2009, as amended on October 26, 2010 (the “First Amendment”) and July 13, 2012 (the “Second Amendment”), pursuant to which NxStage agreed to purchase from PiSA, and PiSA agreed to supply NxStage with certain products (the “Supply Agreement”);

WHEREAS, on November 26, 2012, NxStage notified PiSA in writing that it was assigning the Supply Agreement to its subsidiary and affiliate, MDS;

WHEREAS, PiSA and MDS desire to enter into this Third Amendment to, among other things, enter a Renewal Term through December 31, 2019, revise Appendix A to the Supply Agreement to reflect the minimums and purchase prices starting January 1, 2016 of the Renewal Term, and make certain changes to the projects set forth in the Second Amendment to Supply Agreement.

AGREEMENT

NOW, THEREFORE, in consideration of the foregoing premises and the mutual covenants and agreements provided herein, the parties hereto, intending to be legally bound hereby, agree as follows:

“The parties hereby agree to a renewal term that expires on December 31, 2019 (the “Renewal Term”), unless sooner terminated pursuant to the provisions of this Agreement.

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After such Renewal Term, this Agreement shall be automatically extended for one (1) year periods; provided that either party shall have the right to terminate this Agreement with six (6) months prior written notice of its intent to terminate this Agreement or unless sooner terminated pursuant to the provisions of this Agreement.”

“Consistent with the terms of Section 4.1(c) of the Supply Agreement, the parties have agreed to perform the following projects in order to improve the quality, cost and availability of the 5 liter bicarbonate-based pre-mixed dialysate Product (“Bicarbonate Dialysate”):

The parties agree that time is of the essence in completing these projects, and that PiSA shall endeavor in good faith to proceed as quickly as possible on the projects. The parties have set forth on Appendix B project metrics and estimated timing for PiSA to provide the [**] for Bicarbonate Dialysate.”

For the sake of clarity, the provisions in this Section 4 (Projects), amend and replace the provisions set forth in the Section 5 (Projects) of the Second Amendment to Supply Agreement.

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[Remainder of This Page Intentionally Left Blank]

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IN WITNESS WHEREOF, the parties have executed and delivered this Third Amendment as of the Third Amendment Effective Date.

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APPENDIX A (page 1 of 3)

List of Products and Product Codes

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APPENDIX A (page 2 of 3)

MINIMUM PURCHASE COMMITMENTS FOR LACTATE-BASED

PREMIXED DIALYSATE PRODUCTS

Pricing for 5 liter Lactate-based pre-mixed Dialysate Products

See Technical Agreement for Product Specifications

* The Minimum Purchase Commitment is made by NxStage in exchange for the volume pricing as also specified in this Appendix A.

(1) NxStage agrees to issue Purchase Orders and purchase the Product at the highest cost point according to the above table. PiSA will evaluate the delivered quantities on a semi-annual basis and, within thirty (30) days following the end of the semi-annual period, [**] for all purchases according to the table above. The first semi-annual period shall begin on January 1, 2013. For the purposes of example only, if NxStage accomplishes a semi-annual goal of [**] bags, PiSA will [**] for $[**] (i.e., the price difference will be $[**] per bag ($[**] – $[**]) and [**] bags multiplied by $ [**] equals [**] $[**]).

(2) Pricing is in U.S. dollars. NxStage’s total Product orders for all lactate-based premixed formulations, including any new formulations to be developed, shall be considered in the aggregate when determining whether the Minimum Purchase Commitment has been met. The marked price in the above table shall govern pricing for the Products under this Agreement so long as NxStage meets the Minimum Purchase Commitment or pays for any Unit Shortfall consistent with the terms of Section 2.3.

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APPENDIX A (page 3 of 3)

MINIMUM PURCHASE COMMITMENTS FOR BICARBONATE-BASED

PREMIXED DIALYSATE PRODUCTS

Pricing for 5 liter Bicarbonate-based pre-mixed Dialysate Products

See Technical Agreement for Product Specifications

* The Minimum Purchase Commitment is made by NxStage in exchange for the volume pricing as also specified in this Appendix A.

(1) NxStage agrees to issue Purchase Orders and purchase the Product for any quantity at the cost point according to the above table.

(2) Pricing is in U.S. dollars. NxStage’s total Product orders for all bicarbonate-based premixed formulations, including any new formulations to be developed, shall be considered in the aggregate when determining whether the Minimum Purchase Commitment has been met. The marked price in the above table shall govern pricing for the Products under this Agreement so long as NxStage meets the Minimum Purchase Commitment or pays for any Unit Shortfall consistent with the terms of Section 2.3.

(3) See Item #4 of the Third Amendment.

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APPENDIX B (page 1 of 1)

PROJECT METRICS & ESTIMATED TIMING FOR

PISA TO PROVIDE [**] FOR THE BICARBONATE-BASED

PREMIXED DIALYSATE PRODUCTS

Lead Time: [**] from the Third Amendment Effective Date.

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