Causes of PoTS
In primary PoTS there is no known cause.
In secondary PoTS there is an underlying health condition.
In some cases it is difficult to categorise the type of PoTS due to overlap between the subtypes.
This type often starts suddenly, and sufferers may have had a viral illness, pregnancy, immunisations, surgery or trauma prior to their symptoms starting. It is thought that this form of PoTS might be due to an abnormality of the body’s immune system.
This type seems to afflict teenagers. It usually starts between the ages of 12-14 years old and may follow a very rapid growth spurt, with worsening symptoms until the age of 16. By the age of 19 to 24, about 80% of individuals will have no symptoms. The cause is unclear, but it seems to follow a rapid growth spurt.
Deconditioning (being out of shape) is present in some individuals with PoTS. A traumatic event or illness can result in reduced activity or bedrest. Patients become unfit and the heart doesn’t pump as efficiently as before. This can trigger symptoms of orthostatic intolerance so patients avoid exercise which makes their symptoms worse, leading to more physical inactivity. There is a downward spiral of deconditioning which causes or worsens symptoms of PoTS.
Hyperadrenergic type PoTS appears to be less common. This can appear similar to pheochromocytoma (an adrenaline producing tumour) and tests may be needed to rule this out.
Signs and Symptoms
When upright, individuals experience severe anxiety, tremor, and cold sweaty hands and feet. Also, in a good portion of individuals, there is a significant urge to pass urine after even a short period of time upright. True migraine headaches are also common.
Blood noradrenaline levels are often high. High blood pressure may also occur on standing up.
This type of PoTS is suspected to have a strong genetic component as there is often a family history of this disorder. It is thought to be due to over activation of the sympathetic nervous system on standing. There may be an abnormality in a gene that leads to too much noradrenaline circulating in the body, hence the name ‘hyperadrenergic’.
Mast Cell activation disorder
Mast cell activation disorder needs to be considered in those who have episodes of flushing. Increased noradrenaline in the blood stimulates histamine release causing flushing.
Inappropriate Sinus Tachycardia (IST)
Inappropriate sinus tachycardia (IST) is another condition which has similar symptoms to hyperadrenergic PoTS. Patients with IST have a high heart rate when lying down (around 90-100bpm) which rapidly accelerates with slight exertion or emotional stress. The two conditions can overlap and may share the same underlying causes. Treatment options are similar and need to be tailored to the individual.
Chronic Fatigue Syndrome (CFS)
PoTS may be under diagnosed in those with chronic fatigue syndrome (CFS) and is estimated to affect around 25-50% of people with CFS. It has been suggested that these two conditions may be part of the same group of conditions with similar causes.
30% of patients with PoTS will also have vasovagal syncope (also called the ‘simple faint’). On standing, after the early increase in heart rate, they have a drop in blood pressure. Sometimes their heart rate also drops for a short time and they lose consciousness. However, most patients with PoTS do not faint.
PoTS may develop as a consequence of a number of medical conditions such as:
- Joint Hypermobility Syndrome (JHS)
- Paraneoplastic syndrome
- Systemic Lupus Erythematosis (SLE)
- Sjogren’s syndrome
- Multiple Sclerosis (MS)
- Lyme’s Disease
PoTS may be an early sign of other autonomic system abnormalities such as:
- Multiple System Atrophy (MSA)
- Primary Autonomic Failure (PAF)
Chemicals which may cause PoTS:
- Arsenic poisoning
Joint Hypermobility Syndrome/Ehlers-Danlos Syndrome (EDS) type III)
JHS is an important cause of PoTS. It is an inherited disorder thought to be due to faulty proteins which are the main building block of the body, providing strength and support. As a result, joints can be hyper-mobile and more prone to injury and dislocation. Blood vessels may be more elastic causing pooling of blood in the lower body, tachycardia and symptoms of PoTS.
Patient with a combination of JHS and PoTS often display symptoms at an earlier age than patients with only PoTS and show an increased incidence of migraines and fainting.
Five questions can be used to check for hypermobile joints:
Answers to 2 or more questions suggest that your joints are hypermobile.
- Can you now (or could you ever) place your hands flat on the floor without bending your knees?
- Can you now (or could you ever) bend your thumb to touch your forearm?
- As a child did you amuse your friends by contorting your body into strange shapes OR could you do the splits?
- As a child or teenager did your shoulder or kneecap dislocate on more than one occasion?
- Do you consider yourself double-jointed?
Hakim & Grahame (2003)
Even if you have hypermobile joints, people with Joint Hypermobility Syndrome have additional problems and a diagnosis of JHS cannot be made unless a more detailed examination is carried by a specialist.
Written by: PoTS UK Team
Medically approved by: Dr Satish Raj, Dr John Purvis
Review Date: 1/12/14