There are 2 groups of 'primary' POTS.

POTS - Partial Dysautonomia

This considered to be a 'partial autonomic nervous system dysfunction' (or autonomic dysfunction).^1,6 This is the form that affects most young people. It has other symptoms that are related to the dysfunction of the autonomic system (dysautonomia): problem with temperature regulation, sweat,

It is also believed that it is possible to have POTS without having any autonomic dysfunction.

The problem and how it affects standing up: It is a mild form of damage to the peripheral nerves (which is also called peripheral neuropathy). Because of the damage to the nerves to the blood vessels in the legs, arms, and the abdomen (GI - stomach/intestines), the blood vessels do not get narrower (constrict) when the person stands up. This means they hold more blood in the legs, lower arms and abdomen when the person stands up. This is referred to as "pooling" of blood. The body tries to compensate for the blood pooling by increasing the heart rate.

Who Gets Primary POTS: This form of POTS affects females more than males, 5:1. This is the type of POTS people get after an event like acute febrile illness (presumed to be viral), after pregnancy, surgery, sepsis, or trauma. Some studies have documented test results (ganglionic antibody) that indicate some of the patients with this form of POTS have an autoimmune disorder.³

Patients with this subtype often describe a more gradual start to their symptoms with more symptoms developing over time, as compared to a more abrupt onset described by those with Primary POTS.

In the Mayo experience, It is present in about 30% of the people with POTS.³   Some articles indicate that patients with hyperadrenergic POTS often report more significant tremor, anxiety, and cold sweaty extremities when they stand up.^1,7  These are symptoms that are thought to be due to a higher level of epinephrine or norepinephrine (NE). In the analysis of the patient seen at Mayo, they did not find that the patients with the elevated NE did not have more of these symptoms.³

Other differences:
    •  Many people with this type often have orthostatic high blood pressure (hypertension) when they have orthostatic tachycardia (fast heart rate).⁶
    •  Over half of these patients have migraine headaches.
    •  Some people notice an increase in urinary output after standing up for only a short period of time.
    •  There is often a strong family history.
    •   Some of the patients have a single point mutation that affects the reuptake transporter protein that recycles norepinephrine.

Lab results: They have a higher norepinephrine (NE) level when they stand up (over 600 pg/mL).

Why the elevated NE is important:

People with increased NE levels when standing up tend to have a better response to beta-blocker treatment than people who have a lower amount of NE (<600 pg/mL).³

Other medications may also be more effective. See Management of Hyperadrenergic POTS.

Fluid intake and high salt may not be appropriate for people with the hyperadrenergic form.¹

This is often referred to a condition being "secondary". This means that there is another medical condition present and the POTS has developed as a result of the health problem or damage from the main medical condition. This form of POTS is thought to be different than the primary form. It is believed that there is loss of peripheral autonomic nerves or the peripheral nerves that go to the blood vessels do not respond properly. However, the autonomic nerves that go to the heart still work ok.¹

Diabetes mellitus is a common cause of secondary POTS. Other medical conditions that also get POTS are amyloidosis, sarcoidosis, alcoholism, lupus, Sjögren syndrome, chemotherapy, vitamin deficiencies (vitamin B12 and folate), and heavy metal poisoning.^1,2 Another associated condition is Joint Hypermobility Syndrome (JHS). ²

POTS may also found in people with the "Paraneoplastic Syndrome". This means they have a cancer like an adenocarcinoma of the lung, breast, ovary or pancreas.¹ The POTS usually improves when the cancer has been treated.

Managing Secondary POTS: This type of POTS is managed much the same as the other Orthostatic Intolerance (OI) conditions. However, it may get worse if the main condition gets worse. Also, the management needs to be watched more closely because there is another medical condition present and possibly other medications. This would especially relate to the fluids and salt.

It is known that people with POTS do not do well with exercise. It is one of the symptoms that brings them to the physician. It is part of the symptom-list for POTS.

Deconditioning is often present, especially in people with conditions with prominent fatigue and where there has been prolonged bedrest, such as POTS, fibromyalgia type symptoms⁶ and Chronic Fatigue Syndrome (CFS).

One clinical finding that suggests deconditioning is also present is a larger heart-rate response to exercise than occurs with other people with POTS. grubb ^{2008-patients 11}

More than 1 cause for symptoms: They raise the possibility that in at least some people with POTS, more than 1 thing is causing symptoms. There was an initial event or illness that created orthostatic symptoms. These symptoms led to reduced physical activity, bedrest and deconditioning. When the event that triggered POTS plus prolonged bedrest are combined, some of the continuing symptoms and problem with standing, the deconditioning can be contributing to the continuation of orthostatic problems.

Studies to sort out the POTS, deconditioning & POTS with deconditioning^.6-9
POTS is not only due to inactivity/deconditioning: Adolescents with POTS were studied. Most were deconditioned, however, they studied the heart rate changes with exercise and concluded that the changes in POTS were not solely because of inactivity that resulted in deconditioning.¹²

Deconditioning from prolonged bedrest is not enough to create full-blown POTS - This can cause orthostatic intolerance but it is not documented that it can cause POTS. The experience reported by Tank with cosmonauts.⁹ They concluded that cardiovascular deconditioning (which comes from bedrest or space flight) is not enough to create full-blown POTS. They conclude other factors need to be present to create a full-blown POTS.

For more information, check out the pages on Deconditioning?, Prolonged Bedrest, and Prolonged Bedrest & OI.

Authors's Note:  We will explore more of the information on Deconditioning and POTS, how to tell the difference and what needs to be done to recover. Follow us on Twitter or Facebook to be alerted when more is posted.