When your hands and feet tingle and you cramp often, but the tests are normal

Your hands and feet often tingle, and at night your calf cramps.

People with these symptoms usually come to the hospital worrying about a serious disease. But the nerve tests and the blood tests come back normal. There are people for whom taking magnesium does not hold for long. Then they come back having been told they're "just sensitive."

In these cases, I don't first look at the tingling hands and feet or the cramping calf. I first look at the chemical environment of the body in which the nerve and muscle are immersed.

Why does it tingle and why does it cramp

How easily a nerve and muscle become excited is greatly influenced by the ion concentration outside those cells. Among these, ionized calcium is important. This calcium guards the threshold of the nerve and muscle membranes. When ionized calcium drops, the threshold drops, and even a small stimulus makes the nerve fire easily and the muscle contract on its own. Tingling and cramping are signals that this excitability has risen.

Here there's one pitfall. Ionized calcium is different from the "total calcium" value commonly captured in a blood test. There are cases where total calcium is normal but only the ionized calcium has dropped. So the test is normal while the tingling continues.

Common causes that lower ionized calcium

Among the causes that quietly lower ionized calcium, the one I often encounter is breathing.

When you're nervous or anxious, or when a long-standing habit makes you breathe slightly too much, carbon dioxide leaves the body. Then the blood tips slightly toward alkaline, and in an alkaline environment, calcium binds more onto protein, so ionized calcium decreases. A good number of people whose fingertips, toes, and area around the mouth tingle, whose fingers stiffen, and who cramp easily at night are on this pathway. It shares the same root as that state where you're short of breath but oxygen saturation is normal.

That respiratory alkalosis lowers ionized calcium and raises neuromuscular excitability is content written in textbooks.

I don't see the tingling and cramping in these people as the single problem of "calcium deficiency." When the axis of breathing collapses a little, the acid-base environment of the body wavers, and I see that chemical change spread into the excitability of nerves and muscles as a chain. So in many cases calcium on its own does not hold it for long.

I restore the breath and calm the excitability

I look at two things together.

First, I restore the breathing. I check whether there's a habit of breathing shallow and fast without realizing it, or of often gasping in big breaths. When this breathing is slowly calmed, carbon dioxide finds its place, and the environment that had tipped toward alkaline comes back. For some people, this alone noticeably reduces the tingling.

Second, I stabilize a body whose excitability has risen. This takes time. A nerve and muscle that have been sensitized for a long time do not calm down overnight. Helping the body lower its tension and soothe its environment even during the time it has left the clinic — this is the place herbal medicine takes. It's not a way of replacing the body, but of nudging it from the side so that the body regains its own stability.

Cases where you should go to a hospital first

But tingling and cramping have causes that must absolutely be distinguished. If tingling suddenly comes to only one arm or leg, if there's weakness or paralysis, or if slurred speech comes along with it, you must get emergency care without delay. Nerve damage from diabetes, nerve compression from a neck or lower-back disc, thyroid or parathyroid problems, and kidney dysfunction also produce tingling and cramping. These must be checked first before moving on.

There are further strands on the cramp side

This piece has dealt with one strand — breathing and the body's acid-base environment. But cramps do not arise from this strand alone.

The pressure in the compartment the muscle sits in, the energy it takes to release a muscle, and a tilt on the side of the nerve driving the muscle are each separate matters. Those I have written down in A Calf Cramp Does Not Have Just One Cause.

An intact structure is not a settled environment

That the tests are normal means the structure is sound. What environment the nerve is sitting in is not what that test measures. Tingling is usually the latter story, and that is a different matter from being sensitive. Finding where it tilted is the next piece of work.

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References

• When the body tilts even slightly alkaline, more calcium binds to protein — total calcium stays normal while the usable form falls — Journal of Laboratory and Precision Medicine, 2020
• With tingling hands and feet, diabetes and nerve compression in the neck or back are checked first, and tests can still come back normal — Seoul National University Hospital

Written by Dr. Heo Ji-young (PhD in Korean Medicine Pathology, Kyung Hee University · former Research Professor of Herbology, Kyung Hee University)