60yr person has normal 100/70 BP but occasionally shot up to 160/110+ range even when relax. Dr found no evidence of kidny/heart problem. What is it?

Uncommon causes. This merits a careful cardiovascular consultation, including routine and special blood and urine testing to look for uncommon neuroendocrine causes of hypertension. In addition, blood pressure should be checked sitting and standing daily to document the blood pressure pattern.