San Diego County

3020 Children's Way
MC 5103
San Diego, CA 92123




Rady Children's Specialists of San Diego

Medical Group / IPA


Other Languages


Medical School

Pennsylvania State University


Hershey Medical Center


Hershey Medical Center

Board Certifications

Pediatric Endocrinology, Pediatrics




Dr. Karen Klein is a board-certified pediatric endocrinologist at Rady Children's Hospital-San Diego and an associate clinical professor of pediatrics at UC San Diego School of Medicine.

Earning her medical degree at the Pennsylvania State College of Medicine and completing a residency in pediatrics at the same institution, Dr. Klein went on to complete a fellowship in pediatric endocrinology at the National Institute of Child Health and Development, National Institutes of Health in Bethesda, Md. During her training, she developed a novel laboratory method for measuring very low levels of estrogen, which she has used extensively since that time in clinical research.

Dr. Klein's clinical and research interests include pubertal development and growth, and the treatment of precocious puberty. She has lectured on these topics locally, nationally and internationally, and her work has been published in peer-reviewed journals and textbooks. She also enjoys teaching and mentoring students, residents and fellows.

When not working, Dr. Klein is very involved in her church, community and local high school. She enjoys watching her son play lacrosse and soccer, and watching her daughter play soccer and run track.


Incidence of central precocious puberty more than doubled during COVID-19 pandemic: Single-center retrospective review in the United States.
Trujillo MV, Rungvivatjarus T, Klein KO

Using change in predicted adult height during GnRH agonist treatment for individualized treatment decisions in girls with central precocious puberty.
Trujillo MV, Lee PA, Reifschneider K, Backeljauw PF, Dragnic S, Van Komen S, Yu J, Klein KO

Gonadotropin-releasing hormone analog therapies for children with central precocious puberty in the United States.
Popovic J, Geffner ME, Rogol AD, Silverman LA, Kaplowitz PB, Mauras N, Zeitler P, Eugster EA, Klein KO

No pubertal growth spurt, rapid bone maturation, and menarche post GnRHa treatment in girls with precocious puberty.
Briscoe A, Chen K, Klein KO

Importance of individualizing treatment decisions in girls with central precocious puberty when initiating treatment after age 7 years or continuing beyond a chronological age of 10 years or a bone age of 12 years.
Vargas Trujillo M, Dragnic S, Aldridge P, Klein KO

Phase 3 Trial of a Small-volume Subcutaneous 6-Month Duration Leuprolide Acetate Treatment for Central Precocious Puberty.
Klein KO, Freire A, Gryngarten MG, Kletter GB, Benson M, Miller BS, Dajani TS, Eugster EA, Mauras N

A survey of care pathway and health-related quality of life impact for children with central precocious puberty.
Klein KO, Soliman AM, Grubb E, Nisbet P

Treatment patterns, health resource utilization and costs among central precocious puberty patients treated with leuprolide or histrelin: an examination of the commercial and Medicaid populations.
Klein KO, Soliman AM, Bonafede M, Nelson JK, Grubb E

Use of Gonadotropin-Releasing Hormone Analogs in Children: Update by an International Consortium.
Bangalore Krishna K, Fuqua JS, Rogol AD, Klein KO, Popovic J, Houk CP, Charmandari E, Lee PA, Freire AV, Ropelato MG, Yazid Jalaludin M, Mbogo J, Kanaka-Gantenbein C, Luo X, Eugster EA, Klein KO, Vogiatzi MG, Reifschneider K, Bamba V, Garcia Rudaz C, Kaplowitz P, Backeljauw P, Allen DB, Palmert MR, Harrington J, Guerra-Junior G, Stanley T, Torres Tamayo M, Miranda Lora AL, Bajpai A, Silverman LA, Miller BS, Dayal A, Horikawa R, Oberfield S, Rogol AD, Tajima T, Popovic J, Witchel SF, Rosenthal SM, Finlayson C, Hannema SE, Castilla-Peon MF, Mericq V, Medina Bravo PG

Review of Hormone Replacement Therapy in Girls and Adolescents with Hypogonadism.
Klein KO, Phillips SA

Hyperinsulinemic hypoglycemia in seven patients with de novo NSD1 mutations.
Grand K, Gonzalez-Gandolfi C, Ackermann AM, Aljeaid D, Bedoukian E, Bird LM, De Leon DD, Diaz J, Hopkin RJ, Kadakia SP, Keena B, Klein KO, Krantz I, Leon E, Lord K, McDougall C, Medne L, Skraban CM, Stanley CA, Tarpinian J, Zackai E, Deardorff MA, Kalish JM

Gonadotropin-Releasing Hormone (GnRHa) Therapy for Central Precocious Puberty (CPP): Review of Nuances in Assessment of Height, Hormonal Suppression, Psychosocial Issues, and Weight Gain, with Patient Examples.
Klein KO, Lee PA

Predictors of bone maturation, growth rate and adult height in children with central precocious puberty treated with depot leuprolide acetate.
Klein KO, Dragnic S, Soliman AM, Bacher P

Review and evaluation of patient-centered psychosocial assessments for children with central precocious puberty or early puberty.
Williams VSL, Soliman AM, Barrett AM, Klein KO

Estrogen Replacement in Turner Syndrome: Literature Review and Practical Considerations.
Klein KO, Rosenfield RL, Santen RJ, Gawlik AM, Backeljauw PF, Gravholt CH, Sas TCJ, Mauras N

Clinical practice guidelines for the care of girls and women with Turner syndrome: proceedings from the 2016 Cincinnati International Turner Syndrome Meeting.
Gravholt CH, Andersen NH, Conway GS, Dekkers OM, Geffner ME, Klein KO, Lin AE, Mauras N, Quigley CA, Rubin K, Sandberg DE, Sas TCJ, Silberbach M, Söderström-Anttila V, Stochholm K, van Alfen-van derVelden JA, Woelfle J, Backeljauw PF, International Turner Syndrome Consensus Group

Bone maturation along the spectrum from normal weight to obesity: a complex interplay of sex, growth factors and weight gain.
Klein KO, Newfield RS, Hassink SG

Ultrasensitive estrogen levels at 7 years of age predict earlier thelarche: evidence from girls of the growth and obesity Chilean cohort.
Pereira A, Corvalán C, Uauy R, Klein KO, Mericq V

Randomized clinical trial evaluating metformin versus oral contraceptive pills in the treatment of adolescents with polycystic ovarian syndrome.
Al-Zubeidi H, Klein KO

Is there a role for estrogen activity assays? Recombinant cell bioassay for estrogen: Development and applications.
Klein KO

A pediatrician's guide to central precocious puberty.
Kletter GB, Klein KO, Wong YY

Pharmacokinetics and pharmacodynamics of oral and transdermal 17β estradiol in girls with Turner syndrome.
Taboada M, Santen R, Lima J, Hossain J, Singh R, Klein KO, Mauras N

Importance of leuprolide acetate variable dosing for precocious puberty: a range of acceptable suppression.
Cohen D, Janfaza M, Klein KO

Comparison of three doses of leuprolide acetate in the treatment of central precocious puberty: preliminary results.
Mericq V, Lammoglia JJ, Unanue N, Villaroel C, Hernández MI, Avila A, Iñiguez G, Klein KO

Luteinizing hormone (LH) and estradiol suppression and growth in girls with central precocious puberty: is more suppression better? Are pre-injection LH levels useful in monitoring treatment?
Kunz GJ, Sherman TI, Klein KO

See the full listing of this physician's publications on PubMed, a service of the National Library of Medicine.

PubMed is a third-party website and not affiliated with Rady Children's Hospital-San Diego.

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