What Do People with POTS Lack?: Understanding the Core Deficiencies and Dysfunctions

October 1, 2025 •

5 min read

An estimated 1 to 3 million Americans are affected by Postural Orthostatic Tachycardia Syndrome (POTS), a condition characterized by a rapid heart rate upon standing. For those navigating this complex condition, understanding what do people with POTS lack is a critical step toward effective management and symptom relief.

Quick Summary

Individuals with POTS frequently experience low blood volume, electrolyte imbalances, and autonomic nervous system dysfunction that impairs blood vessel constriction. These underlying issues are responsible for the debilitating symptoms, including dizziness and fatigue, that occur when standing up.

Key Points

Low Blood Volume: A significant portion of POTS patients have hypovolemia, a condition of low circulating blood volume, which exacerbates symptoms upon standing.
Impaired Fluid and Salt Retention: Many individuals with POTS struggle with fluid and electrolyte balance, particularly sodium, which contributes to dehydration and low blood volume.
Autonomic Nervous System Dysfunction: The root cause of POTS lies in a malfunctioning autonomic nervous system, leading to poor blood vessel constriction and exaggerated heart rate responses.
Neurological Issues: Subtypes of POTS can involve small fiber neuropathy, where nerve damage affects the ability of blood vessels to tighten effectively.
Nutrient Deficiencies: Gastrointestinal problems and poor absorption can lead to deficiencies in key nutrients like iron, B vitamins, and vitamin D, further contributing to fatigue.
High Norepinephrine: A hyperadrenergic subtype of POTS is characterized by high levels of norepinephrine, putting the body in a constant state of "fight or flight".
Chronic Dehydration: Issues with fluid retention and absorption, sometimes coupled with GI problems, result in chronic dehydration that intensifies POTS symptoms.

POTS is a complex condition that involves a breakdown in the body's autonomic nervous system, the system responsible for involuntary functions like heart rate and blood pressure. As a result, when a person with POTS stands up, their body struggles to counteract the effects of gravity, leading to a cascade of symptomatic events. The core issues are not merely a single deficiency but a combination of several physiological deficits and dysfunctions that vary from person to person.

The Core Deficiencies in POTS

Low Blood Volume (Hypovolemia)

One of the most common findings in people with POTS is a low circulating blood volume, a condition known as hypovolemia. Studies indicate that as many as 70% of POTS patients may have this issue, with plasma volume deficits averaging around 13%. In a healthy person, shifting from lying down to standing causes a small amount of blood to pool in the lower body. The nervous system compensates by constricting blood vessels and increasing heart rate slightly to maintain blood flow to the brain. For those with hypovolemia, this small loss of blood volume is more significant, requiring the heart to beat much faster and harder to compensate, leading to the characteristic tachycardia.

Impaired Fluid and Salt Retention

Hand-in-hand with low blood volume is the body's impaired ability to retain fluid and electrolytes. Many POTS patients excrete more salt and water than a healthy person, contributing to chronic dehydration and hypovolemia. This can be caused by hormonal issues, such as abnormalities in the renin-angiotensin-aldosterone system, which regulates blood volume and sodium balance. Increased fluid and salt intake are therefore common recommendations for managing POTS symptoms.

Autonomic Nervous System Dysfunctions

At the heart of POTS is a malfunction of the autonomic nervous system. This manifests in several ways, and research has identified different subtypes based on the primary dysfunction:

Blood Vessel Control Problems (Neuropathic POTS): In this subtype, there is damage to the small nerve fibers that regulate the constriction of blood vessels in the legs and core. This results in excessive blood pooling in the lower extremities upon standing, reducing the blood returning to the heart and brain.
Hyperadrenergic State (Hyperadrenergic POTS): Some people with POTS have an overactive sympathetic nervous system, the “fight or flight” branch of the autonomic nervous system. This leads to elevated levels of the stress hormone norepinephrine, causing exaggerated tachycardia, palpitations, and anxiety-like symptoms. In some cases, a deficiency in the norepinephrine transporter (NET) is involved, meaning norepinephrine isn't cleared from the system effectively.
Autoimmune Attack: For a significant minority, POTS may be triggered by a prior infection, leading to an autoimmune response where the body mistakenly attacks parts of the nervous system responsible for autonomic function.

Nutritional Gaps and Absorption Issues

In addition to the circulatory and neurological deficits, some people with POTS face nutritional challenges due to compromised digestion.

Gastrointestinal Problems: GI symptoms like nausea, bloating, and irregular bowel movements are common and can hinder nutrient absorption. This can lead to nutritional deficiencies and make it difficult to maintain adequate fluid intake.
Vitamin and Mineral Deficiencies: Certain nutrient deficiencies are commonly reported in the POTS community, including vitamins B12, D, and iron. These deficiencies can contribute to symptoms such as fatigue and weakness, compounding the effects of POTS.

Comparison of Key POTS Subtype Deficiencies

To illustrate the variability of POTS, here is a comparison of the primary physiological lacks associated with three major subtypes:


Feature	Hypovolemic POTS	Neuropathic POTS	Hyperadrenergic POTS
Primary Deficiency	Abnormally low blood volume, especially plasma volume.	Poor small fiber nerve function in the lower limbs.	Excessive levels of norepinephrine.
Mechanism	The kidneys may excrete too much salt and water, contributing to low blood volume.	Inadequate nerve signaling prevents blood vessels from constricting effectively upon standing.	Overactive sympathetic nervous system causes an exaggerated hormonal response to position changes.
Symptom Profile	Dizziness, rapid heart rate, fatigue, especially after meals.	Blood pooling in hands and feet, cyanosis, and classic orthostatic symptoms.	Prominent palpitations, anxiety, tremulousness, and sometimes increased blood pressure upon standing.

Management Strategies to Address Deficiencies

While there is no cure for POTS, addressing these specific deficiencies can significantly alleviate symptoms.

Fluid and Sodium Management

Increase intake: Healthcare providers often recommend a substantial increase in daily fluid and sodium intake. Goals typically range from 2–3 liters of fluid and 3,000–10,000 mg of sodium daily, but should be tailored to individual needs in consultation with a doctor.
Use salty foods and electrolytes: Incorporate salty foods like broths and pickles, or use salt tablets and electrolyte powders designed for hydration, to help the body retain more fluid.

Lifestyle and Exercise Adjustments

Recumbent exercise: For those with exercise intolerance, recumbent options like swimming, rowing, or using a recumbent bike allow for exercise without aggravating orthostatic symptoms. Gradually building up activity can help increase blood volume over time.
Compression garments: Thigh-high compression socks and abdominal binders can help prevent blood from pooling in the lower body, assisting blood flow back to the heart.
Elevate the head of the bed: Raising the head of the bed can help increase circulating blood volume overnight and make getting up easier in the morning.

Nutritional and Medical Support

Address deficiencies: A dietitian can help identify and address any vitamin and mineral deficiencies that might be contributing to fatigue and other symptoms. Supplements may be recommended in some cases.
Consider medications: While no medications are FDA-approved specifically for POTS, off-label use of drugs like fludrocortisone (to increase blood volume) or beta-blockers (to reduce heart rate) may be prescribed by a specialist.

Conclusion

People with POTS face a complex, multi-systemic challenge rooted in physiological lacks and dysfunctions, including low blood volume, poor fluid retention, and compromised autonomic control. By working with a healthcare team to identify the specific issues at play, targeted strategies can be implemented to manage these deficiencies. Proper hydration, increased salt intake, specialized exercise, and addressing nutritional gaps form the foundation of a comprehensive management plan. The path to improvement is often one of individual trial and error, but focusing on these core deficits offers the best chance for symptom relief and a better quality of life. For additional resources and support, consider visiting the Dysautonomia International website.

Dysautonomia International

Frequently Asked Questions

Many people with POTS primarily lack sufficient circulating blood volume, known as hypovolemia, and the ability to properly regulate blood flow and heart rate when changing posture.

POTS patients often lose salt and fluids easily. Increasing salt intake helps the body retain more water, which in turn increases blood volume and can help alleviate symptoms like dizziness and a rapid heartbeat upon standing.

Yes, some studies have found that individuals with POTS may have lower-than-normal levels of vitamin B12, possibly linked to gastrointestinal issues and impaired absorption.

Low blood volume reduces the amount of blood that returns to the heart. In response, the heart beats faster and more forcefully to compensate and pump enough blood to the brain and vital organs.

Yes, deficiencies in nutrients like iron and certain B vitamins, which are sometimes seen in POTS patients, can contribute to symptoms like fatigue and weakness, worsening the overall impact of the condition.

In neuropathic POTS, there is a deficiency in the proper functioning of small nerve fibers, particularly in the lower limbs. These nerves are crucial for constricting blood vessels, and their failure leads to blood pooling when upright.

In hyperadrenergic POTS, the body lacks proper regulation of norepinephrine. There can be an excess of norepinephrine, or a deficiency in the transporter that clears it, leading to an overactive sympathetic nervous system.

While proper hydration is critical for managing symptoms, POTS is a complex condition with multiple underlying factors. Hydration, along with increased salt, regular exercise, and other lifestyle or medical interventions, is part of a broader treatment plan.

Practical strategies include consuming 2-3 liters of fluids daily, increasing salt intake, wearing compression garments, performing recumbent exercise, elevating the head of the bed, and eating smaller, more frequent meals.