Hypertension with Cardiovascular and Renal Complications: This diagnosis is likely due to the combination of hypertension (HTN), tachycardia, palpitations, shortness of breath (SOB), and ankle swelling, which can indicate heart failure or renal disease secondary to uncontrolled hypertension. The presence of polyuria and polydipsia could also suggest an underlying renal issue or diabetes, but the primary concern is the cardiovascular and renal impact of hypertension.

Diabetes Mellitus: The symptoms of polyuria, polydipsia, and fatigue are classic for diabetes mellitus. The presence of hypertension and potential renal complications also aligns with the long-term effects of diabetes.
Heart Failure: Symptoms such as SOB, fatigue, and ankle swelling are indicative of heart failure, which could be a consequence of long-standing hypertension or other cardiac conditions.
Hyperthyroidism: Although not directly indicated by all symptoms, hyperthyroidism can cause tachycardia, palpitations, fatigue, and potentially contribute to hypertension and other symptoms listed.

Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodic hypertension, tachycardia, palpitations, and sweating. It's crucial to consider due to its potential for severe, life-threatening complications if missed.
Renal Artery Stenosis: A condition that can cause secondary hypertension and potentially lead to renal failure. It's essential to diagnose to prevent long-term renal damage.
Aortic Dissection or Aortic Aneurysm: Although less likely, these conditions can present with sudden onset of severe hypertension and can be life-threatening if not promptly diagnosed and treated.

Primary Aldosteronism: A rare cause of secondary hypertension characterized by excessive production of aldosterone, leading to hypertension, hypokalemia, and sometimes symptoms like fatigue and polyuria.
Cushing's Syndrome: A rare endocrine disorder caused by excess cortisol, which can lead to hypertension, fatigue, and potentially some of the other symptoms listed, though it would be less likely without other specific signs like weight gain or striae.
Thyroid Storm: A life-threatening complication of untreated or undertreated hyperthyroidism, which could present with some of the symptoms listed, particularly tachycardia, palpitations, and potentially hypertension.