Beyond Skin

Claire Reach on what blood biomarkers can reveal about skin health and ageing

Every day, aesthetic practitioners assess skin texture, pigmentation, redness, hydration, laxity and the visible signs of ageing. Clinicians are highly trained to identify what is happening on the surface of the skin and recommend treatments to address it.

Yet many of the biological processes influencing skin quality begin long before they become visible. While aesthetic practitioners are experts in assessing what they can see, the skin is influenced by far more than topical skincare and in-clinic treatments. Inflammation, hormonal changes, nutrient deficiencies, metabolic dysfunction and impaired recovery can all affect collagen production, wound healing, skin barrier function and the rate at which the skin ages, but these underlying drivers are not always apparent during a visual skin assessment. ^{1, 2, 3,4}

This raises an important question: are you only treating what you can see, or are you also considering what you can’t?

There are many ways to gain a deeper understanding of the biological factors influencing skin health. Genetics can reveal predispositions, nutrition influences the building blocks available for repair and regeneration, movement impacts circulation and metabolic health, while sleep plays a critical role in recovery and tissue repair. Blood biomarkers are not the whole picture, but they offer one of the most accessible and evidence-based places to start.

Understanding what is happening beneath the surface allows practitioners to take a broader view of patient care and begin connecting the visible signs of ageing with the underlying physiology that may be driving them.

Why internal health matters for the skin
The skin is the body’s largest organ and one of its most metabolically active.⁵ Approximately 30,000–40,000 skin cells are shed every minute, equating to more than two million skin cells every hour and around 50 million every day.⁶ To maintain this constant renewal, a healthy epidermis produces billions of new keratinocytes daily.⁷

This enormous demand for cellular turnover highlights why nutrient status, hormonal balance, metabolic health and inflammation can all have a profound impact on skin quality. The skin is constantly rebuilding itself, and the quality of that rebuilding process is heavily influenced by the internal environment in which it operates.^1,2

The skin may be visible, but many of the biological processes shaping its appearance are not. Blood biomarkers provide an opportunity to look beneath the surface and gain insight into some of the factors influencing how the skin functions, repairs and ages.⁸ While no single marker can tell the whole story, the following biomarkers can provide a useful starting point for clinicians seeking a deeper understanding of their patient’s skin health.

High sensitivity C-reactive protein (hs-CRP): Measuring inflammation
Chronic low-grade inflammation, often referred to as “inflammaging”, is increasingly recognised as one of the key drivers of biological ageing.⁹ Elevated inflammatory signalling stimulates matrix metalloproteinases (MMPs), enzymes that break down collagen and elastin, while also increasing oxidative stress within the skin.¹⁰ Although inflammation may not always be visible, it can contribute to accelerated ageing, increased skin sensitivity, impaired barrier function and slower healing following aesthetic procedures.¹¹ High-sensitivity CRP provides a useful marker of systemic inflammation and can offer insight into processes that may be influencing skin health beneath the surface.⁹

Cholesterol and lipid markers: Supporting the skin barrier
When cholesterol is discussed in healthcare, the conversation typically centres around cardiovascular risk. However, cholesterol also plays a critical structural role within the skin. Approximately 25% of the lipids in the stratum corneum are composed of cholesterol, working alongside ceramides and free fatty acids to maintain hydration and barrier integrity.¹² While elevated LDL cholesterol remains important from a cardiovascular perspective, it can also act as a signal that warrants a broader look at metabolic health.

Elevated LDL is frequently associated with underlying metabolic dysfunction, including insulin resistance and chronic low-grade inflammation.¹³ These processes can increase oxidative stress, damage collagen and elastin, impair tissue repair and contribute to accelerated skin ageing.¹⁴ As our understanding of skin health evolves, it is becoming increasingly clear that the biological processes driving cardiovascular and metabolic disease may also influence how the skin ages and responds to treatment.

Iron and ferritin: Oxygen delivery and tissue repair
Iron plays a vital role in oxygen transport, energy production and collagen synthesis. It is also required for enzymes involved in the maturation and stabilisation of collagen fibres.¹⁵ Ferritin, which reflects stored iron, can provide valuable insight into whether the body has sufficient reserves to support these processes.¹⁶ Suboptimal iron status has been associated with fatigue, impaired wound healing and hair shedding, while adequate iron availability supports the energy-intensive processes of tissue repair and regeneration that are constantly occurring within the skin.^{15, 17}

Magnesium: Supporting repair, recovery and cellular function
Magnesium is involved in more than 300 enzymatic reactions throughout the body and plays a vital role in cellular energy production, protein synthesis and tissue repair.¹⁸ As the skin continuously renews itself, these processes require a significant amount of energy and cellular activity. Magnesium is also involved in DNA and protein synthesis, both of which are essential to produce new skin cells and maintain healthy tissue.¹⁸

Given that a healthy epidermis produces billions of new keratinocytes every day, the availability of nutrients that support these processes is crucial. In addition, chronic stress can increase magnesium requirements, creating an interesting link between stress, recovery and skin health. While severe deficiency is uncommon, suboptimal magnesium status has been associated with increased oxidative stress and impaired recovery¹⁹, making it a useful marker to consider when assessing the broader foundations of skin health.

Vitamin D: The sunshine vitamin
Unlike most nutrients, vitamin D can be produced by the body when the skin is exposed to sunlight, making it uniquely connected to skin health. Vitamin D receptors are present throughout the skin, and vitamin D plays an important role in immune regulation, skin barrier function and wound healing. Low vitamin D status has also been associated with several inflammatory skin conditions, including psoriasis and atopic dermatitis.²⁰

Vitamin D deficiency is common in the UK, particularly during the autumn and winter months when sunlight exposure is limited. The NHS recommends that everyone consider taking a vitamin D supplement between October and March, with estimates suggesting that around one in six adults have low vitamin D levels.

When supplementation is recommended, many practitioners choose vitamin D3 alongside vitamin K2, as the two nutrients work together in supporting overall health. For clinicians, vitamin D represents one of the most practical biomarkers to assess, discuss and address with patients.²¹

Vitamin B12 and folate: Fuel for cellular renewal
Vitamin B12 and folate are essential cofactors in DNA synthesis and cellular replication, making them particularly important for tissues that rely on continual renewal and repair – skin. Deficiencies in either nutrient can impair cell division and tissue regeneration, potentially affecting wound healing and barrier recovery.

Assessment of vitamin B12 and folate status can therefore provide valuable insight into whether the nutritional requirements needed to support effective skin repair and regeneration are being met.²²

Thyroid function: Regulating skin metabolism
Thyroid hormones influence almost every cell in the body, including those within the skin. They help regulate cellular turnover, sebaceous gland activity, wound healing and overall skin metabolism.²³ Hypothyroidism is often associated with dry, rough skin, puffiness and hair thinning, while hyperthyroidism can contribute to thinning skin and increased sensitivity.²⁴ Measuring thyroid markers such as TSH and free T4 can provide useful context when patients present with skin concerns that seem disproportionate to their age, lifestyle or treatment history.

Oestrogen, progesterone, testosterone and SHBG: Hormones and skin ageing
Sex hormones have profound effects on skin structure and appearance.²⁵ Oestrogen is perhaps the most important, supporting collagen production, hydration, elasticity and skin thickness. This helps explain why women can lose up to 30% of skin collagen during the first five years following menopause.^25,26

Progesterone may contribute to skin hydration and barrier function and works alongside oestrogen to support overall skin health.²⁷ Testosterone contributes to skin thickness, repair and sebaceous gland function, while sex hormone-binding globulin (SHBG) regulates the amount of biologically active hormone available to tissues.²⁸ Together, these hormonal changes can influence dryness, elasticity, healing and the visible signs of ageing, making them particularly relevant in perimenopausal and post-menopausal patients. The skin contains receptors for both oestrogen and progesterone, highlighting the important relationship between hormonal health and skin ageing.^26,27

Liver function and albumin: Supporting recovery and resilience
The liver plays a central role in nutrient processing, hormone metabolism and protein synthesis. Biomarkers such as ALT (Alanine Aminotransferase) can provide insight into liver health²⁹, while albumin reflects the body’s ability to synthesise proteins and maintain physiological resilience.³⁰ This is particularly relevant for skin health, as wound healing requires the coordinated activity of hundreds of proteins involved in tissue repair, immune function and collagen formation.15 Although liver markers are not routinely discussed in aesthetic medicine, they provide useful context when evaluating a patient’s capacity for tissue repair, recovery and overall skin health.

Looking beyond the treatment room
The future of aesthetic medicine is unlikely to be defined solely by better devices, injectables or skincare products. Increasingly, it will be shaped by a deeper understanding of the biological factors influencing the patients sitting in front of us.

A patient’s skin reflects far more than their skincare routine. It is influenced by how they sleep, move, eat, recover, respond to stress and age. Blood biomarkers cannot provide a complete picture of these processes, but they can offer valuable clues and create opportunities for more informed conversations about health, ageing and long-term skin quality.

Forward-thinking clinics are already looking beyond the skin itself, recognising that better patient outcomes often come from understanding the factors that influence skin health beneath the surface. Blood biomarkers provide an accessible first step on that journey. In medical aesthetics, the goal should no longer be limited to treating what is visible. The greater opportunity lies in understanding the biology that influences how patients age, heal and respond to treatment in the first place.

For more information, please visit
http://maphealth.io

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