Types of PoTS
There are a number of factors and disorders causing or associated with the condition but in some cases, a cause is never identified.
PoTS has been reported to commence after an infection such as a viral illness, an acute stressor such as pregnancy or surgery, a traumatic event or immunisation.
PoTS in 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.
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 is less common. This can appear similar to pheochromocytoma (a norepinephrine producing tumour) and tests may be needed to rule this out.
When upright, individuals may experience a sense of 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 norepinephrine levels are often high. Blood pressure may also increase (not fall) on standing up.
Norepinephrine Transporter (NET) Deficiency and Blockers
This type of PoTS is similar to Hyperadrenergic PoTS. There may be an abnormality in a gene that leads to too much norepinephrine circulating in the body. There are many antidepressant and antianxiety drugs (SNRIs) that work, in part, by blocking this transporter. These can increase heart rate and make symptoms worse in some patients.
Other Conditions associated with PoTS
Joint Hypermobility Syndrome
Joint hypermobility syndrome (JHS) which is also called benign joint hypermobility syndrome, Ehlers-Danlos (hypermobility type) or Ehlers-Danlos type III is often associated with PoTS.
Hypermobile joints are common, especially in children. This can be a harmless finding and can even be an advantage in sport. If you can answer yes to two of the following questions it is likely that you have hypermobile joints.
- 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?
Joint hypermobility SYNDROME is NOT the same as joint hypermobility and patients with the syndrome will have some of the following additional features:
- Painful hypermobile joints that may dislocate
- Back pain. Frequent strains and sprains
- Co-ordination problems – clumsiness, delayed walking and writing
- Resistance to local anaesthetics
- Skin changes – soft, velvety, thin, stretchy, poor healing, thin papery scars, stretch marks, drooping lids
- Blue tinge to the whites of the eyes
- Tall and slim with long arms and fingers
- Stress incontinence at a younger age. Rectal prolapse
- Gut problems
- Autonomic nervous system problems - PoTS and low blood pressure
Joint hypermobility syndrome is one of the more common conditions associated with PoTS. It is an inherited condition that can be passed down in families. The underlying problem is thought to be faulty connective tissue protein that is found throughout the body including blood vessels, joints and gut and may lead to stretchy or brittle tissues. Patients who have the combination of JHS and PoTS tend to develop symptoms of PoTS at an earlier age, faint more often and suffer from migraine.
Low Blood pressure
Low blood pressure can be healthy, but if it drops very low on standing it is called orthostatic hypotension and can cause symptoms similar to PoTS. Reflex syncope occurs when a drop in blood pressure results in fainting.
PoTS, low blood pressure and reflex syncope can exist together in the same patient and this combination can be seen in joint hypermobility syndrome and chronic fatigue syndrome.
When blood pressure drops there is sometimes an increase in heart rate. This is called a reactive tachycardia and can look like PoTS.
Treatments for both conditions are similar.
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.
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.
Mast Cell Activation Disorder
This needs to be considered if flushing or allergies are prominent.
Recent research has shown that auto-antibodies affecting the autonomic nervous system are more common in people with PoTS.
Autoimmune conditions that have been associated with PoTS include Sjogrens syndrome and antiphospholipid (Hughes) syndrome. Treatment of underlying conditions can improve symptoms of PoTS.
PoTS may develop as a consequence of a number of other medical conditions such as diabetes, cancer, multiple sclerosis, Lyme disease.