Rounding out a thorough panel are markers of your nutritional and hormonal status. Deficiencies and imbalances here are common, frequently missed, and often produce vague symptoms — fatigue, low mood, brain fog — that are easy to dismiss. Measuring them can be genuinely illuminating.
Learning Objectives
- •Learn the key vitamin and mineral status markers
- •Understand common, often-missed deficiencies
- •Know the basic hormone markers worth checking
⚕️ Education, not medical advice
This course explains what common lab markers mean so you can be an informed, engaged participant in your own health. It is NOT medical advice or a substitute for a clinician. Always interpret your results — and any changes to medication, supplements, or care — with a qualified healthcare professional who knows your full history.
Vitamin D, B12, and iron status
A few nutritional markers are especially worth knowing. VITAMIN D (measured as 25-hydroxy-vitamin D) is very commonly low, especially in less sunny climates, and matters for bone, immunity, and more. VITAMIN B12 deficiency causes fatigue and neurological symptoms and is common in older adults and those eating little animal food. FERRITIN reflects your IRON stores — low ferritin is a frequent, often-missed cause of fatigue (especially in menstruating women), while very high iron has its own risks.
Thyroid: TSH and beyond
From the Endocrine course, recall the thyroid sets your metabolic rate. TSH (thyroid-stimulating hormone) is the standard first screen: a high TSH often means the brain is shouting at an underactive thyroid. Because thyroid problems are common (especially in women) and cause exactly the vague symptoms people dismiss — fatigue, weight change, low mood — TSH is a high-value marker.
Sex hormones, where relevant
Sex hormones (like testosterone and estrogen) can be measured when symptoms or context warrant — for example, evaluating low energy, libido, or menopausal symptoms. As the Endocrine course stressed, these are best interpreted by a clinician against your symptoms and history, not chased toward 'youthful' numbers for their own sake. Measure with a purpose, not just to optimize a number.
VITAMIN D (25-OH-D) commonly low; bone, immunity, more VITAMIN B12 deficiency → fatigue, neurological symptoms FERRITIN (iron) low = common missed cause of fatigue TSH (thyroid) standard thyroid screen; high = underactive SEX HORMONES when symptoms/context warrant (clinician-guided)
Why 'I'm just tired all the time' is worth a blood test
Persistent fatigue is one of the most common complaints — and several of these markers are among the most common, fixable causes: low vitamin D, low B12, low iron (ferritin), or an underactive thyroid. Each is easy to test and often very treatable. Chronic tiredness that's chalked up to 'just being busy' is frequently a measurable, correctable deficiency hiding in plain sight.
Vitamins & hormones, by the numbers
- ▸Vitamin D is commonly low, especially in less sunny climates
- ▸Low ferritin (iron) is a frequent, often-missed cause of fatigue
- ▸B12 deficiency is common in older adults and those eating little animal food
- ▸TSH is the standard thyroid screen — thyroid issues cause vague, dismissible symptoms
Persistent tiredness is just a normal part of a busy life, not something to test.
Chronic fatigue is frequently a measurable, fixable deficiency — low vitamin D, B12, or iron (ferritin), or an underactive thyroid. These are easy to test and often very treatable, so persistent tiredness is worth investigating rather than dismissing.
Quick Check
Which marker reflects your iron STORES and is a common missed cause of fatigue?
Quick Check
What is TSH used to screen for?
True or False
Several common causes of persistent fatigue (low vitamin D, B12, iron, or thyroid issues) are easily measured by blood tests.
Summary
- →Vitamin D, B12, and ferritin (iron) reveal common, often-missed deficiencies
- →TSH is the standard thyroid screen for an underactive thyroid
- →Sex hormones are measured when symptoms warrant, interpreted with a clinician
- →Many cases of persistent fatigue are measurable, fixable deficiencies
You now know the major markers. The final lesson ties it together: how to build your own panel, track it, and turn numbers into action.