POWER OF ATTORNEY

     Know all persons by these presents, that the undersigned hereby constitutes
and appoints each of John P. Butler, Jason A. Amello and Nicole R. Hadas,
signing singly, as the undersigned's true and lawful attorney-in-fact to:

     (1)   prepare, execute in the undersigned's name and on the undersigned's
           behalf, and submit to the U.S. Securities and Exchange Commission
           (the "SEC") a Form ID, including amendments thereto, and any other
           documents necessary or appropriate to obtain codes and passwords
           enabling the undersigned to make electronic filings with the SEC of
           reports required by Section 16(a) of the Securities Exchange Act of
           1934, as amended (the "Act") or any rule or regulation of the SEC;

     (2)   execute for and on behalf of the undersigned, in the undersigned's
           capacity as an officer, director and/or shareholder of Akebia
           Therapeutics, Inc. (the "Company"), Forms 3, 4 and 5 in accordance
           with Section 16(a) of the Act, and the rules thereunder;

     (3)   do and perform any and all acts for and on behalf of the undersigned
           that may be necessary or desirable to complete and execute any such
           Form 3, 4 or 5 and timely file such form with the SEC and any stock
           exchange or similar authority; and

     (4)   take any other action of any type whatsoever in connection with the
           foregoing that, in the opinion of such attorney-in-fact, may be of
           benefit to, in the best interest of, or legally required by, the
           undersigned, it being understood that the documents executed by such
           attorney-in-fact on behalf of the undersigned pursuant to this Power
           of Attorney shall be in such form and shall contain such terms and
           conditions as such attorney-in-fact may approve in such attorney-in-
           fact's discretion.

     The undersigned hereby grants to each attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary or proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or revocation,
hereby ratifying and confirming all the acts such attorney-in-fact shall
lawfully do or cause to be done by virtue of this Power of Attorney and the
rights and powers herein granted.  The undersigned acknowledges that each of the
foregoing attorneys-in-fact, in serving in such capacity at the request of the
undersigned, is not assuming any of the undersigned's responsibilities to comply
with Section 16 of the Act.

     This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to each
of the foregoing attorneys-in-fact.

     IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of December 13th, 2018.

                                        Signature:    /s/  Michael W. Rogers
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                                        Printed Name: Michael W. Rogers
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