Serum tests are performed by drawing blood from a patient and spinning it down to separate the cellular components from the liquid serum, which contains soluble analytes such as hormones. While lacking the convenience and long-term stability of dried blood spot, serum can be used to measure a wider array of analytes.

Why Measure in Serum?

Blood serum is a broadly accepted method for measuring a wide variety of analytes including steroid, thyroid and peptide hormones (e.g., LH & FSH). In certain cases, it offers a suitable alternative to measuring hormones in salivadried blood spot and dried urine.

Serum vs. Blood Spot vs. Saliva vs. Urine Hormone Testing

Serum testing is a reliable method for measuring endogenous hormones – those produced naturally by the body. For patients not supplementing with hormones, serum is just as accurate as any of the other testing methods offered by ZRT.

For patients who supplement with patch or pellet steroid hormones, serum testing is also a reliable method. However, for patients who supplement with oral, topical or vaginal steroid hormones, saliva and blood spot provide more accurate results. Refer to our Testing & Supplementing Guide below for recommendations on ideal uses for each testing method.

Serum testing is not something new to ZRT. When we first developed finger-prick dried blood spot testing for steroids, thyroid hormones, and peptide hormones over twenty years ago, we normalized the results to the same hormones derived from venipuncture serum. For endogenously produced hormones we found dried blood spot and serum results to be quantitatively equivalent, making the transition from capillary whole blood dried on filter paper (dried blood spot) to serum testing simple. Today, we have expanded our serum testing to offer a wider variety of analytes available to test.

Review our Testing & Supplementing Guide

Why Use Serum When Dried Blood Spot Works so Well?

For practitioners, some are just more familiar with serum/plasma test results and want to stick with that method of testing. For patients, sometimes it is easier to get insurance reimbursement with serum testing. For ZRT, there are a few tests we have wanted to commercialize but have not been able to develop in dried blood spot.

Serum Tests Available

Analytes we offer in serum cover some of the most common female and male hormones associated with the endocrine system, which encompasses our most popular tests that evaluate the hypothalamic-pituitary-gonadal (estradiol, progesterone, testosterone, LH, FSH, prolactin (PRL)), adrenal (DHEAS, cortisol), and thyroid (free T3, free T4, TSH, TPOab) axes.

We also offer a serum test for ferritin (iron status), which is linked to thyroid hormone and hemoglobin synthesis. Iron is an essential element required for the thyroid-synthesizing enzyme thyroid peroxidase, and for the iron present in red blood cells. 

Other tests in the profiles include homocysteine, folate (vitamin B9), and vitamin B12, which can help to evaluate methylation pathways that play essential roles in:

  • DNA and RNA synthesis
  • Methylation of DNA, neurotransmitters, and catechol estrogens
  • Recycling of homocysteine to methionine
  • Degradation of homocysteine to alpha-ketobutyrate for the Citric Acid Cycle
  • Formation of cysteine, an amino acid essential for synthesis of the universal antioxidant glutathione

Production of methyl groups used in many of the above biochemical pathways is essential for health of the cardiovascular and nervous systems, and safe steroid hormone metabolism through methylation/inactivation of catechol estrogens.

Learn more about ZRT's serum profiles in our Female & Male Profiles in Serum Provider Data Sheet and our Methylation & Memory Profiles in Serum Provider Data Sheet.

The ZRT Difference

ZRT's reports include a range of patient symptoms, which provide deeper insight into patient conditions. We also include personalized comments created by an AI developed at ZRT that helps correlate hormone levels and symptoms to deliver real understanding. This is unique to ZRT – not something that any other serum testing lab can provide.

See the Profiles

To restore the vital balance of hormones, we first need a detailed, accurate measurement of hormone levels. Not just numbers, but an assessment that offers real meaning.

Serum Testing
ZRT Laboratory Serum Kit

Currently, serum kits are only available by phone or email.

To order your serum kit, please contact our customer service team at 866.600.1636 or

Serum Test Kit Includes:

Female Serum Hormones - Basic: E2, Pg, T, DS, C, SHBG & TSH 

Male Serum Hormones - Basic:  E2, T, DS, C, SHBG, PSA & TSH

Female and Male Hormone Basic profiles are a good start for understanding if your sex hormones, adrenal hormones, and thyroid hormone marker (TSH) are well balanced.

Female Serum Hormones - Advanced: E2, Pg, T, DS, C, SHBG, TSH, fT3, fT4, TPOab, FSH, LH & FER (Sample Report)

Male Serum Hormones - Advanced: E2, T, DS, C, SHBG, PSA, TSH, fT3, fT4, TPOab, LH, PRL & FER

The Female and Male Hormone Advanced profiles provide a broader overview of the health and balance of your sex hormones and thyroid hormones. Pituitary hormones (LH, FSH, PRL) are included that control ovarian production of the sex hormones (E2, Pg, T) and help define menopausal status. Iron status, determined by ferritin, is included. PSA and prolactin are included in the Male Hormone Profiles as a prescreen for testosterone therapy to exclude prostate issues and pituitary prolactinoma.

Methylation: FER, FOL, HCY & B12

This profile comprises an assessment of nutrients involved as cofactors in the biosynthesis of neurotransmitters important for memory and brain function, and in the methylation processes that ensure the toxic compound homocysteine is converted to methionine. Methionine is in turn converted to S-adenosyl methionine, which serves to donate methyl groups to a variety of substrates involved in the synthesis and activation/inactivation of neurotransmitters, steroids (e.g., COMT/SAMe methylation/inactivation of catechol estrogens), proteins, and nucleic acids.

Reference Information

Testing Catalog

ZRT Test Directory

Serum Reference Ranges


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