Ask-Upmark kidneys are a cause of secondary hypertension that can be curable.

It is thought to be congenital or the consequence of vesicoureteral reflux.

When a diagnosis of multicystic kidney is made in utero by ultrasound, the disease is found to be bilateral in many cases. Those with bilateral disease often have other severe deformities or polysystemic malformation syndromes. In bilateral cases, the newborn has the classic characteristic of Potter's syndrome.

The bilateral condition is incompatible with survival, as the contralateral system frequently is abnormal as well. Contralateral ureteropelvic junction obstruction is found in 3% to 12% of infants with multicystic kidney and contralateral vesicoureteral reflux is seen even more often, in 18% to 43% of infants. Because the high incidence of reflux, voiding cystourethrography usually has been considered advisable in all newborns with a multicystic kidney.

In patients with this condition, the central portion of the kidney may be found just inferior to the inferior mesenteric artery because the normal embryologic ascent of the kidneys is arrested by its presence in people with central fusion of the kidneys. Horseshoe kidney is often asymptomatic, though persons affected by this condition may experience nausea, abdominal discomfort, kidney stones and urinary tract infections at greater frequency than those without renal fusion. There is currently no treatment for renal fusion other than symptomatic treatment.

Imaging Findings -

The 2 kidneys on opposite sides of the body with the lower poles fused in midline. Midline or symmetrical fusion (90% of cases).

May be missed on US, therefore pay careful attention to identification of lower poles of kidneys.

Renal long axis medially orientated,

Lower poles with curved configuration, elongation and poorly defined

Isthmus crosses midline anterior to spine and great vessels.

US for diagnosis in utero

IVP followed by CT or scintigraphy for pre-operative assessment

Variant arterial supply -

Bilateral renal arteries,

Inferior mesenteric Artery,

Arteries arising from aorta or common iliac, internal iliac, external iliac or inferior mesenteric arteries.

The lower poles of these kidneys fuse in the midline anterior to the aorta and spine. The isthmus is usually located at L4/5 level between the aorta and IMA.

Nuclear medicine (DMSA) scan confirms horseshoe kidney with fusion of both renal lower poles.

While most cases of horseshoe kidneys are asymptomatic and discovered upon autopsy, the condition may increase the risk for:

- Kidney obstruction – abnormal placement of ureter may lead to obstruction and dilation of the kidney.

- Kidney infections – associated with vesicoureteral reflux.

- Kidney stones – deviant orientation of kidneys combined with slow urine flow and kidney obstruction may lead to kidney stones.

- Kidney cancer – increased risk of renal cancer, especially Wilms' tumor, transitional cell carcinoma, and an occasional case report of carcinoid tumor. Despite increased risk, the overall risk is still relatively low.

The prevalence of horseshoe kidneys in females with Turner Syndrome is about 15%.

It can be associated with trisomy 18.

It can be associated with venous anomalies like left sided IVC 9.

Many forms of cystic kidney disease can be detected in children prior to birth. Abnormalities which only affect one kidney are unlikely to cause a problem with the healthy arrival of a baby. Abnormalities which affect both kidneys can have an effect on the baby's amniotic fluid volume which can in turn lead to problems with lung development. Some forms of obstruction can be very hard to differentiate from cystic renal disease on early scans.

Cystic kidney disease refers to a wide range of hereditary, developmental, and acquired conditions. With the inclusion of neoplasms with cystic changes, over 40 classifications and subtypes have been identified. Depending on the disease classification, the presentation of disease may be from birth, or much later into adult life. Cystic disease may involve one or both kidneys and may or may not occur in the presence of other anomalies. A higher incidence of cystic kidney disease is found in the male population and prevalence increases with age. Renal cysts have been reported in more than 50% of patients over the age of 50. Typically, cysts grow up to 2.88 mm annually and cause related pain and/or hemorrhage.

Of the cystic kidney diseases, the most common is Polycystic kidney disease; having two prevalent sub-types: autosomal recessive and autosomal dominant polycystic kidney disease. Autosomal Recessive Polycystic Kidney Disease (ARPKD) is primarily diagnosed in infants and young children. Autosomal dominant polycystic kidney disease (ADPKD) is most often diagnosed in adulthood.

Another example of cystic kidney disease is Medullary sponge kidney.

Medullary sponge kidney (also known as Cacchi–Ricci disease) is a congenital disorder of the kidneys characterized by cystic dilatation of the collecting tubules in one or both kidneys. Individuals with medullary sponge kidney are at increased risk for kidney stones and urinary tract infection (UTI). Patients with MSK typically pass twice as many stones per year as do other stone formers without MSK. While described as a "benign" disorder with a low morbidity rate, as many as 10% of patients with MSK have an increased risk of morbidity associated with frequent stones and UTIs. While some patients report increased chronic kidney pain, the source of the pain, when a UTI or blockage is not present, is unclear at this time. Renal colic (flank and back pain) is present in 55% of patients. Women with MSK experience more stones, UTIs, and complications than men. MSK was previously believed not to be hereditary but there is more evidence coming forth that may indicate otherwise.

Signs and symptoms include high blood pressure, headaches, abdominal pain, blood in the urine, and excessive urination. Other symptoms include pain in the back, and cyst formation (renal and other organs).

Most cases are asymptomatic or are discovered during an investigation of blood in the urine. Symptomatic patients typically present as middle-aged adults with renal colic, kidney stones, nephrocalcinosis and/or recurrent urinary tract infections; however, MSK also may affect children very rarely. In addition to the typical clinical phenotype of recurrent stone disease, other clinical profiles have now been recognized, that is, an indolent, almost asymptomatic MSK, and a rare form characterized by intractable pain.

Multicystic dysplastic kidney (MCDK) is a condition that results from the malformation of the kidney during fetal development. The kidney consists of irregular cysts of varying sizes. Multicystic dysplastic kidney is a common type of renal cystic disease, and it is a cause of an abdominal mass in infants.

Polycystic kidney disease (PKD or PCKD, also known as polycystic kidney syndrome) is a genetic disorder in which the renal tubules become structurally abnormal, resulting in the development and growth of multiple cysts within the kidney. These cysts may begin to develop before birth or in infancy, in childhood, or in adulthood. Cysts are non-functioning tubules filled with fluid pumped into them, which range in size from microscopic to enormous, crushing adjacent normal tubules and eventually rendering them non-functional also.

PKD is caused by abnormal genes which produce a specific abnormal protein which has an adverse affect on tubule development. PKD is a general term for two types, each having their own pathology and genetic cause: autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD). The abnormal gene exists in all cells in the body: as a result, cysts may occur in the liver, seminal vesicles, and pancreas. This genetic defect can also cause aortic root aneurysms, and aneurysms in the circle of Willis cerebral arteries, which if they rupture, can cause a subarachnoid hemorrhage.

Diagnosis may be suspected from one, some, or all of the following: new onset flank pain or red urine; a positive family history; palpation of enlarged kidneys on physical exam; an incidental finding on abdominal sonogram; or an incidental finding of abnormal kidney function on routine lab work (BUN, serum creatinine, or eGFR). Definitive diagnosis is made by abdominal CT exam.

Complications include hypertension due to the activation of the renin–angiotensin–aldosterone system (RAAS), frequent cyst infections, urinary bleeding, and declining renal function. Hypertension is treated with angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs). Infections are treated with antibiotics. Declining renal function is treated with renal replacement therapy (RRT): dialysis and/or transplantation. Management from the time of the suspected or definitive diagnosis is by a board-certified nephrologist.

In terms of the signs/symptoms of medullary cystic kidney disease, the disease is not easy to diagnose and is uncommon. In this condition, loss of kidney function occurs slowly over time, however the following signs/symptoms could be observed in an affected individual:

Some individuals with this disease develop gout, which is a condition in which patients develop severe pain and swelling in the big toe or another joint such as the knee. If untreated, it becomes chronic and affects the joints most of the time, instead of intermittently.

Infantile, juvenile, and adolescent forms of nephronophthisis have been identified. Although the range of characterizations is broad, people affected by nephronophthisis typically present with polyuria (production of a large volume of urine), polydipsia (excessive liquid intake), and after several months to years, end-stage kidney disease, a condition necessitating either dialysis or a kidney transplant in order to survive. Some individuals that suffer from nephronophthisis also have so-called "extra-renal symptoms" which can include tapetoretinal degeneration, liver problems, ocularmotor apraxia, and cone-shaped epiphysis (Saldino-Mainzer syndrome).

Renal failure is defined by functional impairment of the kidney. Renal failure can be acute or chronic, and can be further broken down into categories of pre-renal, intrinsic renal and post-renal.

Pre-renal failure refers to impairment of supply of blood to the functional nephrons including renal artery stenosis. Intrinsic renal diseases are the classic diseases of the kidney including drug toxicity and nephritis. Post-renal failure is outlet obstruction after the kidney, such as a kidney stone or prostatic bladder outlet obstruction.

Renal failure may require medication, dietary and lifestyle modification and dialysis.

Primary renal cell carcinomas as well as metastatic cancers can affect the kidney.

The signs and symptoms of hydronephrosis depend upon whether the obstruction is acute or chronic, partial or complete, unilateral or bilateral. Hydronephrosis that occurs acutely with sudden onset (as caused by a kidney stone) can cause intense pain in the flank area (between the hips and ribs). Historically, this type of pain has been described as "Dietl's crisis". Conversely, hydronephrosis that develops gradually will generally cause either attacks of a dull discomfort or no pain. Nausea and vomiting may also occur. An obstruction that occurs at the urethra or bladder outlet can cause pain and pressure resulting from distension of the bladder. Blocking the flow of urine will commonly result in urinary tract infections which can lead to the development of additional stones, fever, and blood or pus in the urine. If complete obstruction occurs, kidney failure may follow.

Blood tests may show impaired kidney function (elevated urea or creatinine) or electrolyte imbalances such as hyponatremia or hyperchloremic metabolic acidosis. Urinalysis may indicate an elevated pH due to the secondary destruction of nephrons within the affected kidney. Physical examination may detect a palpable abdominal or flank mass caused by the enlarged kidney.

Nephronophthisis is a genetic disorder of the kidneys which affects children. It is classified as a medullary cystic kidney disease. The disorder is inherited in an autosomal recessive fashion and, although rare, is the most common genetic cause of childhood kidney failure. It is a form of ciliopathy. Its incidence has been estimated to be 0.9 cases per million people in the United States, and 1 in 50,000 births in Canada.

Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent, potentially lethal, monogenic human disorder. It is associated with large interfamilial and intrafamilial variability, which can be explained to a large extent by its genetic heterogeneity and modifier genes. It is also the most common of the inherited cystic kidney diseases — a group of disorders with related but distinct pathogenesis, characterized by the development of renal cysts and various extrarenal manifestations, which in case of ADPKD include cysts in other organs, such as the liver, seminal vesicles, pancreas, and arachnoid membrane, as well as other abnormalities, such as intracranial aneurysms and dolichoectasias, aortic root dilatation and aneurysms, mitral valve prolapse, and abdominal wall hernias. Over 50% of patients with ADPKD eventually develop end stage kidney disease and require dialysis or kidney transplantation. ADPKD is estimated to affect at least 1 in every 1000 individuals worldwide, making this disease the most common inherited kidney disorder with a diagnosed prevalence of 1:2000 and incidence of 1:3000-1:8000 in a global scale.

The prognosis of hydronephrosis is extremely variable, and depends on the condition leading to hydronephrosis, whether one (unilateral) or both (bilateral) kidneys are affected, the pre-existing kidney function, the duration of hydronephrosis (acute or chronic), and whether hydronephrosis occurred in developing or mature kidneys.

For example, unilateral hydronephrosis caused by an obstructing stone will likely resolve when the stone passes, and the likelihood of recovery is excellent. Alternately, severe bilateral prenatal hydronephrosis (such as occurs with posterior urethral valves) will likely carry a poor long-term prognosis, because obstruction while the kidneys are developing causes permanent kidney damage even if the obstruction is relieved postnatally.

Hydronephrosis can be a cause of pyonephrosis - which is a urological emergency.

Dent's disease often produces the following signs and symptoms:

- Extreme thirst combined with dehydration, which leads to frequent urination

- Nephrolithiasis (kidney stones)

- Hypercalciuria (high urine calcium - >300 mg/d or >4 mg/kg per d) with normal levels blood/serum calcium)

- Aminoaciduria (amino acids in urine)

- Phosphaturia (phosphate in urine)

- Glycosuria (glucose in urine)

- Kaliuresis (potassium in urine)

- Hyperuricosuria (excessive amounts of uric acid in the urine)

- Impaired urinary acidification

- Rickets

In a study of 25 patients with Dent's disease, 9 of 15 men, and one of 10 women suffered end-stage kidney disease by the age of 47.

Symptoms can vary from person to person. Someone in early stage kidney disease may not feel sick or notice symptoms as they occur. When kidneys fail to filter properly, waste accumulates in the blood and the body, a condition called azotemia. Very low levels of azotaemia may produce few, if any, symptoms. If the disease progresses, symptoms become noticeable (if the failure is of sufficient degree to cause symptoms). Kidney failure accompanied by noticeable symptoms is termed uraemia.

Symptoms of kidney failure include the following:

- High levels of urea in the blood, which can result in:

- Vomiting or diarrhea (or both) which may lead to dehydration

- Nausea

- Weight loss

- Nocturnal urination

- More frequent urination, or in greater amounts than usual, with pale urine

- Less frequent urination, or in smaller amounts than usual, with dark coloured urine

- Blood in the urine

- Pressure, or difficulty urinating

- Unusual amounts of urination, usually in large quantities

- A buildup of phosphates in the blood that diseased kidneys cannot filter out may cause:

- Itching

- Bone damage

- Nonunion in broken bones

- Muscle cramps (caused by low levels of calcium which can be associated with hyperphosphatemia)

- A buildup of potassium in the blood that diseased kidneys cannot filter out (called hyperkalemia) may cause:

- Abnormal heart rhythms

- Muscle paralysis

- Failure of kidneys to remove excess fluid may cause:

- Swelling of the legs, ankles, feet, face, or hands

- Shortness of breath due to extra fluid on the lungs (may also be caused by anemia)

- Polycystic kidney disease, which causes large, fluid-filled cysts on the kidneys and sometimes the liver, can cause:

- Pain in the back or side

- Healthy kidneys produce the hormone erythropoietin that stimulates the bone marrow to make oxygen-carrying red blood cells. As the kidneys fail, they produce less erythropoietin, resulting in decreased production of red blood cells to replace the natural breakdown of old red blood cells. As a result, the blood carries less hemoglobin, a condition known as anemia. This can result in:

- Feeling tired or weak

- Memory problems

- Difficulty concentrating

- Dizziness

- Low blood pressure

- Normally, proteins are too large to pass through the kidneys, however, they are able to pass through when the glomeruli are damaged. This does not cause symptoms until extensive kidney damage has occurred, after which symptoms include:

- Foamy or bubbly urine

- Swelling in the hands, feet, abdomen, or face

- Other symptoms include:

- Appetite loss, a bad taste in the mouth

- Difficulty sleeping

- Darkening of the skin

- Excess protein in the blood

- With high doses of penicillin, people with kidney failure may experience seizures

Renal ectopia or ectopic kidney describes a kidney that is not located in its usual position. It results from the kidney failing to ascend from its origin in the true pelvis or from a superiorly ascended kidney located in the thorax.

It has an incidence of approximately 1/900.

Medullary cystic kidney disease (MCKD) is an autosomal dominant kidney disorder characterized by tubulointerstitial sclerosis leading to end-stage renal disease. Because the presence of cysts is neither an early nor a typical diagnostic feature of the disease, and because at least 4 different gene mutations may give rise to the condition, the name autosomal dominant tubulointerstitial kidney disease (ADTKD) has been proposed, to be appended with the underlying genetic variant for a particular individual. Importantly, if cysts are found in the medullary collecting ducts they can result in a shrunken kidney, unlike that of polycystic kidney disease. There are two known forms of medullary cystic kidney disease, mucin-1 kidney disease 1 (MKD1) and mucin-2 kidney disease/uromodulin kidney disease (MKD2). A third form of the disease occurs due to mutations in the gene encoding renin (ADTKD-REN), and has formerly been known as familial juvenile hyperuricemic nephropathy type 2.

Urologic disease can involve congenital or acquired dysfunction of the urinary system.

Kidney diseases are normally investigated and treated by nephrologists, while the specialty of urology deals with problems in the other organs. Gynecologists may deal with problems of incontinence in women.

Diseases of other bodily systems also have a direct effect on urogenital function. For instance, it has been shown that protein released by the kidneys in diabetes mellitus sensitises the kidney to the damaging effects of hypertension.

Diabetes also can have a direct effect on urination due to peripheral neuropathies which occur in some individuals with poorly controlled diabetics.

The hallmark of a stone that obstructs the ureter or renal pelvis is excruciating, intermittent pain that radiates from the flank to the groin or to the inner thigh. This pain, known as renal colic, is often described as one of the strongest pain sensations known. Renal colic caused by kidney stones is commonly accompanied by urinary urgency, restlessness, hematuria, sweating, nausea, and vomiting. It typically comes in waves lasting 20 to 60 minutes caused by peristaltic contractions of the ureter as it attempts to expel the stone.

The embryological link between the urinary tract, the genital system, and the gastrointestinal tract is the basis of the radiation of pain to the gonads, as well as the nausea and vomiting that are also common in urolithiasis. Postrenal azotemia and hydronephrosis can be observed following the obstruction of urine flow through one or both ureters.

Pain in the lower left quadrant can sometimes be confused with diverticulitis because the sigmoid colon overlaps the ureter and the exact location of the pain may be difficult to isolate due to the close proximity of these two structures.