Diabetic Nephropathy with Dehydration: This condition is a leading cause of kidney disease and can lead to polydipsia (excessive thirst) due to high blood sugar levels. Dehydration from inadequate fluid intake or excessive urine production can cause syncope (fainting), tachycardia (rapid heart rate), and kidney pain.

Pyelonephritis: An infection of the kidney, which can cause kidney pain, and if severe, can lead to systemic symptoms such as tachycardia and syncope. Polydipsia might be present due to fever or the body's attempt to flush out the infection.
Nephrolithiasis (Kidney Stones): Can cause severe kidney pain and may lead to polydipsia if the patient is trying to increase fluid intake to help pass the stone. Tachycardia and syncope can occur if the pain is severe or if there is associated dehydration.
Dehydration: From any cause can lead to polydipsia, tachycardia, and syncope. Kidney pain might be referred or due to concentrated urine.

Sepsis: Although less likely, sepsis from a urinary tract infection or other sources can present with these symptoms and is life-threatening if not promptly treated.
Renal Infarction: A blockage of the blood flow to the kidney can cause severe pain, and if bilateral or in a solitary kidney, can lead to acute kidney injury, presenting with these symptoms.
Hyperglycemic Hyperosmolar Nonketotic Syndrome (HHNS): A serious complication of diabetes that can cause severe dehydration, leading to tachycardia, syncope, and polydipsia.

Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodes of tachycardia, hypertension, and might lead to kidney pain if there is associated kidney disease. Polydipsia could be present due to hyperglycemia caused by the tumor's effect on glucose metabolism.
Vasculitis: Certain types of vasculitis, like ANCA-associated vasculitis, can affect the kidneys and cause pain, and if severe, can lead to systemic symptoms including those listed.