One of the biggest failures of treating chronic skin rash issues is seeing your skin as disconnected from the rest of your body. Newsflash — it’s not.

One of the most frustrating aspects of working with clients is the sheer number who’ve never had any sort of labs run. Labs that could provide clues as to what’s causing your skin to flare and rash.

Because your skin doesn’t live in a bubble operating totally separate from the rest of your body.

SOMETHING is clearly going on — not just some notion that you have a steroid cream deficiency.

If your skin rash condition is not getting better, your next step is to request blood labs.

I realize that it’s unfortunately not par for the course that dermatologists will run labs. Typically they’ll ask about your symptoms and hopefully take a look at the problem. Maybe they’ll do a biopsy.

But surprisingly, a diagnosis is made without running a single lab test! And it’s one very clear reason that you could continue to suffer. Since there are at least 15 different root causes that trigger skin rashes, looking deeper can hold many valuable clues.

Your skin’s health is a sign that something within your body is off.

That’s why getting labs done can help you create an effective treatment strategy that frees you from managing your rashes on a daily basis.


Two scientists doing tests in a laboratory

Why Lab Tests are Important for Skin Conditions

Accurately diagnosing skin conditions can be tricky – even for a professional.

Many skin conditions are difficult to diagnose because they look similar to each other.(1) Plenty of experts and doctors who’ve been guests on the Healthy Skin Show have admitted this to me.

Plus, there are times when diagnosis without lab work ends up missing more systemic issues lurking under the surface and driving the skin issues.

When hidden root causes are missed or a diagnosis is wrong, you continue to suffer.

That’s why looking at the total picture helps to get an accurate diagnosis and a better understanding of the root cause of the problem. Your skin is ultimately connected to everything else in your body, and it’s time to acknowledge that.

And that shift will take time and our collective voice reminding our medical system that we don’t just want “band-aids” for the rashes. We want solutions that require more thought and an “all things are connected” approach.

At this moment, few dermatologists will run labs beyond the occasional skin biopsy/scraping. The refusal to run blood labs is baffling because there is plenty of valuable information to be found from them. And it’s not as if running them is outside the scope of what a medical doctor is allowed to do.

So many people (including myself) suffer for what seems like an unending period of time. All because no one is willing to look at your problem from a different perspective that could (and often does) yield pretty important information.

That’s why during my initial session with clients reviewing previous lab work, I’ll put together a list of labs. You’ll probably discover that your dermatologist will say NO to running them and so your best bet is either asking your PCP or running them yourself.

By the time you’re finished reading this, you’ll know what labs to request and WHY it’s so important to do this!


Young woman taking care of her skin

How Your Skin Is Connected To Other Parts Of Your Body

Your skin rashes aren’t happening in a vacuum.

There are underlying drivers that help to trigger or even perpetuate flares.

And even though our medical system has become overly accustomed to cutting up your body into pieces, it’s really failing each of us. Because you’re the person who has to live with this day in and day out.

If it seems like a new concept to you that your skin rash condition could be connected to other areas of your body, here’s a couple of examples.

Psoriasis is an autoimmune disease that is linked to:

  • Genetics
  • Weight
  • The environment and diet (e.g. cold temperatures, trauma, infections, microbiome, alcohol use)
  • Certain medications
  • Systemic inflammation
  • Your immune system’s response to perceived “intruders” (2)

To make it even more complex, the treatment for psoriasis differs when there is arthritis present which happens up to 30% of the time.(2)

Another common issue is eczema (or atopic dermatitis) which is linked to:

  • Disrupted epidermal barrier via genetics
  • Dietary triggers
  • Stress
  • Environmental allergies
  • Inflammatory factors
  • Nutrient insufficiencies
  • Thyroid function
  • Mast-cell activation & histamine
  • Skin microbiome disruptions
  • Abnormal immune system response(3)

Rosacea has been connected to SIBO (small intestine bacteria overgrowth) which happens in the gut for a variety of reasons.

The list goes on and on because of the connections between skin rash issues and systemic imbalances.

And it demonstrates why doing labs is important!

Especially considering that the “one-size-fits-all” approach to treating skin conditions is not very effective and may not help your skin get better.(3)

To be clear, blood labs aren’t going to give you a diagnosis of what type of condition you have.

Instead, you use them to better understand what’s going wrong beneath the surface preventing your body from rebuilding healthy skin. The most effective strategy is to get a panel of tests that can give you the most accurate assessment.(3)

Let’s dig into the tests I recommend and why I recommend them.


Woman blowing dandelion seeds that can cause allergies

Autoimmune, Inflammatory and Allergy Labs

Inflammation is a huge factor when it comes to skin health. Too much inflammation can wreak havoc on so much of your body, including your skin.

Inflammation is often the result of an overactive immune system.

This is why it’s so important to check if you have any hidden immune or autoimmune issues. Not only do they manifest on your skin (e.g. psoriasis) but once you have one autoimmune disease, you’re at higher risk of developing others.

Lab tests are key here!

1 – CBC (Complete Blood Cell)

A CBC lab is very commonly run even with routine health exams. It’s also ordered when a person is experiencing symptoms that suggest infection or inflammation.(4,5)

If the test comes back with abnormal levels of white blood cells, this indicates potential infection or inflammation. If the test shows low levels of red blood cells, this can indicate that you’re low in vitamin B12 and folate.(4,5)

2 – ESR (Erythrocyte sedimentation rate)

The ESR test looks at your erythrocytes (red blood cells) and how they react with the proteins in your blood. Your ESR test results are higher when you have higher levels of inflammation.(6) The ESR test can help to determine what kind of psoriasis you have (e.g. pustular and erythrodermic).(2)

The ESR is a measure of inflammation levels over time, which makes it really useful.(6)

3 – CRP (C-Reactive Protein)

CRP also measures the body’s inflammation, but in a different way.

It is an immune protein that changes much quicker than the ESR does, so this is a good measure of current levels of inflammation (as opposed to inflammation over time).(6) CRP levels are higher in people with psoriasis.(7,8)

4 – Plasma histamine

Exposure to an allergen causes an immune reaction that releases a compound called histamine.(9) When there are too many of the histamine-releasing cells (mast cells) in the skin, it causes swelling and inflammation that looks like a rash and/or hives. It also can cause lots of unwanted itching.(9,10)


Healthy vegetables full of vitamins and minerals

Tests for Levels of Essential Vitamins and Minerals

A healthy balance of essential vitamins and minerals is important for overall health. Some vitamins and minerals are especially important for skin health.

Having your levels tested before supplementing is an important step because having too much or too little of one can throw off the balance of other nutrients and even cause side effects.

5 – Serum Vitamin D test

About one-third of Americans are at risk of low vitamin D.(11)

Vitamin D helps with inflammation by promoting the skin’s immune system.(12) Low vitamin D levels are linked with both atopic dermatitis and psoriasis.(12,13)

Several studies show that when vitamin D levels are low, supplementing with it can be safe and effective for skin conditions.(14)

Before supplementing with vitamin D, make sure your levels are low. Optimal levels of serum Vitamin D is between 50 to 80 ng/mL.

Too much vitamin D can cause blood levels of calcium to get too high which can become dangerous. If you supplement with vitamin D, it’s important to continue getting your blood vitamin D levels monitored.(14)

6 – Serum Vitamin A test

Vitamin A is an antioxidant and plays a crucial role in healthy skin and allergic skin inflammation. Several skin conditions, such as atopic dermatitis, have been associated with low levels of vitamin A.(15)

In fact, prescription-only high level of vitamin A is an FDA-approved effective treatment for several skin conditions such as acne, severe chronic hand eczema and psoriasis.(16,17,18,19)

Too much vitamin A, however, can be dangerous which underscores why you must test before supplementing.

Hypervitaminosis A can cause dizziness, nausea, headaches, coma, and even death. High intakes of vitamin A in pregnant women can cause birth defects in their babies.(19) This is why it’s important to get your vitamin A levels tested.

7 – RBC/Erythrocyte Zinc test

Zinc is an essential mineral needed for over 100 enzymes in the body. It’s important for many cellular functions including wound healing, immunity and keeping inflammation at bay.(20,21)

When it comes to skin, about 11% of the body’s zinc is associated with the epidermis (the outermost layer of skin).(22) Zinc deficiency is linked to hair loss and rashes like atopic dermatitis.(20,21)

After people with atopic dermatitis who were low on zinc supplemented for eight weeks, they had normal levels.(21) More importantly, they had noticeable improvements in their skin. It was less red and thick, had a better moisture barrier and was less itchy.(21,23)

While zinc is an essential mineral, too much can lead to gut symptoms and dizziness. Longer-term, this can lead to side effects including deficiencies in other minerals.(21)

Please note that this test is an erythrocyte test, not the serum value. There is a big difference between the two because the erythrocyte tests show what your cells actually have available for use. Serum values do not provide this sort of information.

8 – RBC/Erythrocyte magnesium test

Magnesium is another essential mineral that’s required for healthy bones and teeth as well as for muscle and nerve function. It’s also necessary for hundreds of enzymes in the body and is used for energy, metabolism and replication.(22,24)

As a result, magnesium is required to activate your body’s energy building block, known as ATP. Every process in the body, including healthy cellular turnover, needs an ample supply of ATP to do its job. Without it, biochemical processes begin to struggle.(25)

And again note that this is an erythrocyte test, NOT a serum value.

9 – Vitamin B12, folate (vitamin B9) and homocysteine

Several skin conditions and treatments for skin conditions are linked with imbalances in the body’s vitamin B12, folate and homocysteine levels. In fact, vitamin B tests are often ordered to see if a deficiency is causing skin issues like rash, dermatitis, sores on the lips or in the mouth, and cracks at the corners of the mouth.(26)

Ideally, we want healthy levels of vitamin B12 and folate to avoid deficiencies. We also want low levels of homocysteine because high homocysteine indicates that there could be low vitamin B6 and difficulty producing glutathione (a potent antioxidant). Elevations are also linked with heart disease and neuropsychiatric disorders.(18)

People with psoriasis are known to have a higher risk of heart disease. In fact, a recent study found that the link between psoriasis and heart disease may be low levels of folate and high levels of homocysteine.(27)

Homocysteine levels are high in people with acne.(28) One of the treatments for acne is high doses of vitamin A. The problem here is it can throw off the vitamin balance and cause low levels of vitamin B12 and folate.(18)

For some people, it’s a great idea to take a B-complex that helps to balance the nutrient levels needed to support your body. Just be aware that the type of B vitamins your body needs vary based on genetics for methylation.

Thyroid Hormones and Metabolism Labs

10 – Full thyroid panel

The thyroid gland in your neck helps maintain your body temperature and metabolism. It tells your cells how quickly they should do things like turnover or produce energy (both of which are important to building healthy skin).

When the critical hormones secreted by your thyroid gland are out of balance, it can also throw your skin out of balance. Skin symptoms of imbalanced thyroid hormones include rashes and pale, dry skin.(29)

A full thyroid panel includes these recommended tests:

  • TSH
  • FREE T3
  • FREE T4
  • Reverse T3
  • Thyroid antibodies – Measures if your immune system is fighting your thyroid gland by mistake (autoimmune disease). It includes TPO and Thyroglobulin antibodies. (30,31)

When you know your lab results for these thyroid tests, you will know whether your skin issues may be caused by an underlying thyroid issue.

Thyroid issues are more common than you’d think. 1 in 8 women has low thyroid function which underscores why you want to get this checked.

11 – CMP (Comprehensive Metabolic Panel)

Having a CMP lab done is important because it includes 14 tests that measure different aspects of your metabolism. These tests look at kidney and liver function – two organs that need to be running smoothly in order to be healthy and have healthy skin.(32,33)

This lab can determine, for example, whether you have metabolic syndrome. Metabolic syndrome is strongly linked with psoriasis. In fact, the more severe your psoriasis is, the stronger the link. Even having mild psoriasis puts you at a higher risk of developing metabolic syndrome.(34)

Skin Biopsy, Scraping, Infections, and Microbiome

Looking at the skin under a microscope can show the health of the skin cells. It can also show if there are infections of “bad” microbes and also the balance of “good” microbes that help the skin stay healthy.

Your skin has its own microbiome that plays a crucial role in its health. This is affected by antibiotics for bacterial infections or antifungals for overgrowth of candida or other fungal strains on the skin.

12 – Skin Biopsy or Scraping

Taking a small sample of skin can determine whether your skin condition is due to a bacterial and/or fungal infection. Having an infection can worsen skin conditions like psoriasis (e.g. hand and foot) so knowing whether you have one is so important.(2)

More and more research shows the roles that the skin microbiome plays on many skin conditions. For example, having a lower diversity or imbalance of skin microbes is linked with psoriasis.(35)

If your labs show an imbalance in your skin’s microbiome, there are topical probiotics you can try.


Scientist using microscope for skin test


Remember, these tests do not give you a diagnosis. Instead, they look at your body as a whole to better understand where it could be struggling.

If you’ve had ongoing skin rash issues for longer than 6 months that haven’t improved with the “run of the mill” recommendations, then it’s time to dig. There are certainly other labs that can be requested, but those aren’t necessary for everyone.

Functional labs can lend a huge helping hand — these are some of the ones I use in my clinical practice.

If you are looking for custom and more targeted recommendations of what to do next, you can set up time here for me to review your case.

Or if you're looking to get these labs ordered yourself (or a portion), you can do so HERE.

Knowing what to ask for and what stones need to be turned over so you can get past the flare cycle is key!



1 – https://www.niams.nih.gov/health-topics/psoriasis#tab-diagnosis

2 – https://emedicine.medscape.com/article/1943419-workup#c2

3 – https://insights.ovid.com/pubmed?pmid=26226355

4 – https://labtestsonline.org/tests/complete-blood-count-cbc

5 – https://medlineplus.gov/ency/article/003642.htm

6 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2832720/

7 – https://www.ncbi.nlm.nih.gov/pubmed/23998353

8 – https://www.ncbi.nlm.nih.gov/pubmed/23550658

9 – https://medlineplus.gov/ency/article/001466.htm

10 – https://labtestsonline.org/tests/histamine

11 – https://www.cdc.gov/nchs/data/databriefs/db59.htm

12 – https://www.ncbi.nlm.nih.gov/pubmed/30238557

13 – https://medlineplus.gov/lab-tests/vitamin-d-test/

14 – http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-42302018000700643&lng=en&nrm=iso&tlng=en

15 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6213761/

16 – https://www.ncbi.nlm.nih.gov/pubmed/27992140

17 – https://en.wikipedia.org/wiki/Alitretinoin

18 – https://www.ncbi.nlm.nih.gov/pubmed/30207526

19 – https://ods.od.nih.gov/factsheets/VitaminA-Consumer/

20 – https://www.merckmanuals.com/home/disorders-of-nutrition/minerals/zinc

21 – https://www.medicaljournals.se/acta/content/html/10.2340/00015555-1772

22 – https://onlinelibrary.wiley.com/doi/full/10.1111/j.1468-2494.2012.00731.x

23 – https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/transepidermal-water-loss

24 – https://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/overview-of-magnesium-s-role-in-the-body

25 – https://amzn.to/2LktIwV, pg 84

26 – https://labtestsonline.org/tests/b-vitamins

27 – https://www.ncbi.nlm.nih.gov/pubmed/30074615

28 – https://www.ncbi.nlm.nih.gov/pubmed/29159884

29 – https://www.womenshealth.gov/a-z-topics/thyroid-disease

30 – https://medlineplus.gov/thyroidtests.html

31 – https://www.niddk.nih.gov/health-information/diagnostic-tests/thyroid

32 – https://labtestsonline.org/tests/comprehensive-metabolic-panel-cmp#

33 – https://medlineplus.gov/ency/article/003468.htm

34 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312178/

35 – https://www.ncbi.nlm.nih.gov/pubmed/27875351

Jennifer Fugo, MS, CNS

Jennifer Fugo, MS, CNS is an integrative Clinical Nutritionist and the founder of Skinterrupt. She works with women who are fed up with chronic gut and skin rash issues discover the root causes and create a plan to get them back to a fuller, richer life.

Follow Us

Medical Disclaimer

Skinterrupt offers health, wellness, fitness and nutritional information which is designed for educational purposes only. You should not rely on this information as a substitute for, nor does it replace, professional medical advice, diagnois, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other health care professional. Do not disregard, avoid, or delay obtaining medical or health related advise from your physician or other health care professional because of something you may have seen or read on our site, or in our advertising, marketing, or promotional materials. The use of any information provided by Skinterrupt is solely at your own risk.

Nothing stated or posted on our site, or in our advertising, marketing or promotional materials, or through any of the services we offer, as intended to be, and must not be taken to be, the practice of medicine or counseling care. For purposes of this disclaimer, the practice of medicine or counseling care includes, without limitation, nutritional counseling, psychiatry, psychology, psychotherapy, or providing health care treatment, instruction, diagnosis, prognosis, or advice.