NIH Clarifies Instructions to Grantees on Incorporating Sex as a Biological Variable

In 2014, in response to requests by the Endocrine Society, the National Institutes of Health (NIH) announced that it would develop policies to require investigators to account for sex as a fundamental biological variable in NIH-supported preclinical research.

The Endocrine Society wholeheartedly supports the goal of ensuring that sex is considered in studies funded by the NIH, and we are in agreement that a significant component of the rigor and completeness in research, in many or most contexts, is the investigation of sex-specific effects. The Society also believes a consideration of sex as a biological variable is an important component of efforts to ensure that clinical trials are designed on sound biologic principles and prior findings.

The Endocrine Society has closely followed efforts by NIH to craft and implement policies to ensure the consideration of sex as a biological variable in research studies. Recently, in his monthly newsletter to the extramural community, the NIH deputy director for Extramural Research, Michael Lauer, MD, shared that NIH seeks to clarify the expectations of NIH on the inclusion of sex as a biological variable. The post references an earlier publication in the FASEB Journal by Janine Clayton, MD, director of the NIH Office of Research on Women’s Health (ORWH), about how sex should be considered across the entire biomedical research spectrum from basic research through population health studies. The publications attempt to delineate what NIH means by considering sex as a biological variable, and distinguish the consideration of sex as a variable from the conduct of sex differences research.

The Endocrine Society has been influential in the ongoing effort by NIH to implement workable policies for researchers to appropriately consider biological sex in research grants and publications. For instance, in a response to a Request for Information (RFI) on incorporating sex as a biological variable, we highlighted specific ways in which NIH can facilitate the consideration of sex as a biological variable. In addition, the Endocrine Society and the Society for Women’s Health Research (SWHR) co-sponsored a Congressional briefing designed to educate members of Congress and their staff about the need to include both sexes in all phases of biomedical research. Speakers included Endocrine Society Past-President Teresa K. Woodruff, PhD.

The Society appreciates that many researchers have important questions about how to appropriately include sex as a biological variable in their research proposals and publications. We are appreciative that Lauer is trying to clarify what will be required, but we also understand that the research community may still require more information on how they and grant reviewers are expected to interpret the new policy.

The Endocrine Society will continue to engage the NIH and ORWH on this issue and we encourage interested members to send their questions, suggestions, and comments to Joseph Laakso, PhD., Associate Director of Science Policy at

Laakso is the associate director for Science Policy at the Endocrine Society.

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