This is very interesting,
Is there any information or studies/papers on POTS and left renal vein compression that I can read upon?
There is very little in the way of research articles in the literature about how LRV causes POTS, only mention that there is a connection.
I have had some exchanges with a transplant surgeon in the US who is currently working on a paper about it and he is of the opinion that increased venous pressure in the adrenal gland causes a problem either with aldosterone or norepinephrine but also agrees with research findings that increased venous pressure in the kidney reduces the renin ouput to impact on the renin-angiotensin-aldosterone system in a way that is not yet fully elucidated. The latter has only been studied in chronic kidney disease though.
There is no one symptom set. Hematuria is the most common finding but it's absent in about 20% of cases.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2878259/
[Takebayashi et al
61 clinically differentiate NCS into 3 subtypes: idiopathic renal bleeding, massive orthostatic proteinuria (protein level >400 mg/dL), and severe orthostatic intolerance that markedly impairs activities of daily living.
5 Severe orthostatic intolerance, as previously described by Stewart et al,
66 is accompanied by LRV occlusion in 70% of cases. Idiopathic renal bleeding and massive orthostatic proteinuria are seen in 18% and 14% of patients, respectively,
5 and are caused by lysis of red blood cells in the urine.
67 Degrees of proteinuria vary depending on postural changes.
43
Chronic fatigue syndrome and fatigue symptoms have been associated with NCS with high LRV-IVC pressure gradients.
19,
66,
68 Fatigue symptoms correlated positively with high peak velocity (PV) ratios by DUS and improved in some patients after surgery, balloon angioplasty, or aspirin therapy.
3,
68,
69/ ]
https://www.ncbi.nlm.nih.gov/pubmed/22573421
https://www.ncbi.nlm.nih.gov/pubmed/16047645