There is a particular kind of exhaustion that does not go away with sleep. You rest, you recover, you do everything right, and you still wake up feeling like you are running on empty. Your hair is shedding more than usual. You cannot focus. Your heart races for no reason. You feel cold when nobody else does.

You mention it to your doctor. They run bloodwork. Everything comes back normal.

But here is the thing, normal and optimal are not the same. And there are four specific markers that are frequently missed, frequently low in women, and frequently the reason you feel the way you do.

Iron and ferritin: the ones most commonly missed

Iron is the mineral your body uses to produce hemoglobin, the protein that carries oxygen through your blood. Ferritin is the protein that stores that iron. Think of iron as the cash in your wallet and ferritin as your savings account you can look fine on the surface while your reserves are completely depleted underneath.

This is exactly why ferritin matters so much. When your body starts running low on iron, it drains your ferritin stores first, often long before your iron levels look abnormal on a standard panel. Which means you can have bloodwork that reads “normal” while your body is already symptomatic and struggling.

Low ferritin in women looks like: persistent fatigue that sleep does not fix, hair thinning or shedding, brain fog, shortness of breath with minimal exertion, heart palpitations, restless legs at night, and feeling cold all the time. Sound familiar?

A ferritin level under 30 ng/mL is worth a conversation with your doctor. Under 50 if you are symptomatic. These are not emergency numbers, they are simply a signal that your body could use some support.

If oral iron has not worked well for you in the past, and for many women it causes constipation and nausea and absorbs poorly, IV iron is a safe, effective alternative that delivers directly into the bloodstream and works significantly faster. It is not a last resort. For many women, especially postpartum, it is the smarter first move.

Vitamin B12: the deficiency that hides in plain sight

B12 is essential for nerve function, red blood cell production, and brain health. And because it shares so many symptoms with low iron, fatigue, brain fog, tingling in the hands or feet, mood changes, memory issues, it often goes undetected simply because nobody thinks to check it alongside ferritin.

Women who follow plant-based or vegetarian diets are at higher risk, as B12 is found almost exclusively in animal products. But even women who eat meat can be deficient if their gut is not absorbing it efficiently, which becomes more common with age, certain medications like metformin, and after pregnancy.

A B12 level below 300 pg/mL is considered suboptimal by many practitioners, even if it technically falls within the “normal” lab range. Supplementing is simple and safe, but it is worth knowing your actual number first.

Vitamin D: The one almost everyone is low in.

Vitamin D deficiency is one of the most common nutritional gaps in the world, and women are particularly affected. Despite the name, vitamin D functions more like a hormone, it plays a role in immune function, mood regulation, bone health, muscle strength, and energy levels.

Low vitamin D does not always announce itself dramatically. It often shows up as a general sense of fatigue, low mood, getting sick frequently, or muscle aches that seem to have no clear cause. Many women live with suboptimal levels for years without knowing.

The sweet spot for vitamin D is generally considered to be between 40 and 60 ng/mL. Sun exposure helps, but for most people living modern indoor lives, supplementation is usually necessary to reach and maintain those levels. Your doctor can check yours with a simple blood test.

What to actually do with this information?

None of this is meant to send you down a rabbit hole of anxiety about your labs. Most women who are low in one or more of these nutrients are not dealing with a serious medical condition, they are dealing with a body that has been giving a lot and not getting quite enough back.

The goal is not perfection. It is just having the information you need to feel like yourself.

At your next appointment, ask your doctor to check your ferritin, B12, and Vitamin D specifically, not just a general iron panel. These are straightforward tests, and knowing your numbers gives you something concrete to work with.

You are not imagining it or just overthinking, your body has been trying to tell you something ang just needed someone to help you listen.