The symptoms of acute kidney injury result from the various disturbances of kidney function that are associated with the disease. Accumulation of urea and other nitrogen-containing substances in the bloodstream lead to a number of symptoms, such as fatigue, loss of appetite, headache, nausea and vomiting.[4] Marked increases in the potassium level can lead to irregularities in the heartbeat, which can be severe and life-threatening.[5] Fluid balance is frequently affected, though hypertension is rare.[6] The construct of renal angina has been developed to assist with detection of early signs of kidney injury.