Common Diseases of the Kidneys
Chronic Kidney Disease
CKD is a progressive decline in renal function, demonstrated by an estimated glomerular filtration rate under 60 for three or more months, resulting in a buildup of waste products in the blood, and in electrolyte imbalances and anemia. Albumin to creatinine ratio may also be used to establish a diagnosis of CKD. Other blood, urine, and kidney imaging tests may also indicate CKD (Cohen 2010; Ferri 2014c).
Features of CKD include progressive retention of nitrogenous waste products in the blood (uremia), electrolyte imbalance, metabolic acidosis, and anemia (Duranton 2012). While prolonged exposure to acute insults such as drugs or infection are capable of causing CKD, chronic conditions such as diabetes mellitus and hypertension are more commonly the cause (Mehdi 2009; Cohen 2010).
Acute Kidney Injury
Acute kidney injury is a rapid impairment of renal function that occurs in a matter of hours or days. Acute kidney injury can result from insults within the kidney itself (renal causes), reduction of blood flow into the kidney (prerenal causes), or damage to the lower urinary tract that causes the backup of uremic toxins into the kidney (postrenal causes) (Ferri 2014a; NKF 2013b).
Blood flow to the kidneys can be reduced by hemorrhage, dehydration, heart failure, pulmonary embolism, sepsis (a systemic inflammatory response caused by infection of the blood), excessive blood calcium, and some drugs, such as nonsteroidal anti-inflammatory drugs (NSAIDs) (Ferri 2014a).
The kidneys may be directly damaged by autoimmune disease, lymphoma, infection, certain medications, and conditions that lead to rapid tissue breakdown (Ferri 2014a).
The urinary tract can be damaged by obstruction of the ureters, bladder, or urethra by stones, tumors, prostatic hyperplasia, trauma, or infection (Ferri 2014a; Elsevier BV 2012).
Kidney stone(s), a condition also known as nephrolithiasis, is one of the most common kidney diseases. There are several types of kidney stones, each composed of an accumulation of a different type of compound naturally present in the body, and having different risk factors for their formation. Calcium oxalate stones are the most common kidney stones in humans, accounting for 76% of stones; their most common cause is high urine calcium levels (Finkielstein 2006). Other relatively common stones include calcium phosphate, usually due to high urine pH; uric acid, common in cases of acidic urine and patients with gout or metabolic syndrome; struvite, often the result of urinary tract infections; and cystine, resulting from genetic disorders of amino acid transport (Elsevier BV 2012).