Fatigue and reduced exercise tolerance are prominent symptoms of both conditions, and dysautonomia may underlie both conditions.POTS can sometimes be a paraneoplastic syndrome associated with cancer.There are case reports of people developing POTS and other forms of dysautonomia post-COVID. There is no good large-scale empirical evidence yet to prove a connection, so for now the evidence is preliminary. Diagnosis
POTS is most commonly diagnosed by a cardiologist (41%), cardiac electrophysiologist (15%), or Neurologist (19%). The average number of physicians seen before receiving diagnosis is seven, and the average delay before diagnosis is 4.7 years. Diagnostic criteria
A POTS diagnosis requires the following characteristics:
For patients age 20 or older, increase in heart rate ≥30 bpm within ten minutes of upright posture (tilt table test or standing) from a supine position
For patients age 12–19, heart rate increase must be >40 bpm
Associated with related symptoms that are worse with upright posture and that improve with recumbence
Chronic symptoms that have lasted for longer than six months
In the absence of other disorders, medications, or functional states that are known to predispose to orthostatic tachycardia

Orthostatic intolerance
An increase in heart rate upon moving to an upright posture is known as orthostatic (upright) tachycardia (fast heart rate). It occurs without any coinciding drop in blood pressure, as that would indicate orthostatic hypotension. Certain medications to treat POTS may cause orthostatic hypotension. It is accompanied by other features of orthostatic intolerance—symptoms that develop in an upright position and are relieved by reclining.
Diagnosis
Clinical evaluation
Female infants with classic CAH have ambiguous genitalia due to exposure to high concentrations of androgens in utero. CAH due to 21-hydroxylase deficiency is the most common cause of ambiguous genitalia in genotypically normal female infants (46XX). Less severely affected females may present with early pubarche. Young women may present with symptoms of polycystic ovarian syndrome (oligomenorrhea, polycystic ovaries, hirsutism).Males with classic CAH generally have no signs of CAH at birth. Some may present with hyperpigmentation, due to co-secretion with melanocyte-stimulating hormone, and possible penile enlargement. Age of diagnosis of males with CAH varies and depends on the severity of aldosterone deficiency. Boys with salt-wasting disease present early with symptoms of hyponatremia and hypovolemia. Boys with non-salt-wasting disease present later with signs of virilization.In rarer forms of CAH, males are undermasculinized  and females generally have no signs or symptoms at birth. Laboratory studies
Genetic analysis can be helpful to confirm a diagnosis of CAH, but it is not necessary if classic clinical and laboratory findings are present. In classic 21-hydroxylase deficiency, laboratory studies will show:

Hypoglycemia (due to hypocortisolism) - One of cortisols many functions is to increase blood glucose levels. This occurs via a combination of several mechanisms, including (a) the stimulation of gluconeogesis (i.e. the creation of new glucose) in the liver, (b) the promotion of glycogenolysis (i.e. the breakdown of glycogen into glucose), and (c) the prevention of glucose leaving the bloodstream via the downregulation of GLUT-4 receptors (which normally promote movement of glucose from the bloodstream into adipose and muscle tissues).