Essential Hypertension: This is the most common cause of hypertension in adults, accounting for about 90-95% of cases. It is a diagnosis of exclusion, made after ruling out secondary causes of hypertension. The patient's age and the absence of any specific symptoms or signs suggestive of a secondary cause make essential hypertension the most likely diagnosis.

Primary Aldosteronism: A condition characterized by excessive production of aldosterone, leading to hypertension and hypokalemia. It is more common in women and often presents in middle age.
Chronic Kidney Disease (CKD): Hypertension is both a cause and a consequence of CKD. The patient's age and potential for undiagnosed kidney disease make CKD a plausible diagnosis.
Sleep Apnea: This condition is associated with hypertension, and its prevalence increases with age. The patient's age and potential for obesity or other risk factors for sleep apnea make it a consideration.

Pheochromocytoma: A rare tumor of the adrenal gland that secretes catecholamines, leading to episodic or sustained hypertension. Although rare, it is critical to diagnose due to the potential for severe, life-threatening hypertension.
Aortic Coarctation: A congenital narrowing of the aortic isthmus, which can present with hypertension in adulthood, especially if previously undiagnosed.
Cushing's Syndrome: A condition caused by excess cortisol, which can lead to hypertension among other symptoms. It is essential to consider due to its potential for significant morbidity if left untreated.

Hyperparathyroidism: Elevated parathyroid hormone levels can lead to hypertension, although this is a less common cause.
Thyroid Disease: Both hyperthyroidism and hypothyroidism can be associated with hypertension, though they are less common causes.
Renal Artery Stenosis: A narrowing of the renal arteries, which can cause hypertension due to activation of the renin-angiotensin-aldosterone system. It is more common in certain populations, such as those with atherosclerosis or fibromuscular dysplasia.