Brief Answer:
Hormonal or vascular causes apart from renal and cardiac cause

Detailed Answer:
Hello

Thanks for the query

Unlike adults primary hypertension(hereditary/diet/life style related) is uncommon in children. In children the secondary hypertension is most commonly occur due to renal problems.Cardiac cause is the second commonest.
Apart from renal or cardiac the cause of hypertension in children can be vasculitis(SLE, Henoch scholein purpura) or hormonal causes(hyperparathyroidism,hyperparathyroidism or adrenal gland abnormality).There can be other uncommon causes also and should be evaluated after ruling out these two.

If the renal and cardiac evaluation came to be normal the next step should be to rule out vascular or hormonal causes.
Please provide me details,so that I better help you out.

I would be glad to answer if you have any further query.
Regards

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