Nephrocalcinosis is diagnosed for the most part by imaging techniques. The imagings used are ultrasound (US), abdominal plain film and CT imaging. Of the 3 techniques CT and US are the more preferred. Nephrocalcinosis is considered present if at least two radiologists make the diagnosis on US and/or CT. In some cases a renal biopsy is done instead if imaging is not enough to confirm nephrocalcinosis. Once the diagnosis is confirmed additional testing is needed to find the underlying cause because the underlying condition may require treatment for reasons independent of nephrocalcinosis. These additional tests will measure serum, electrolytes, calcium, and phosphate, and the urine pH. If no underlying cause can be found then urine collection should be done for 24 hours and measurements of the excretion of calcium, phosphate, oxalate, citrate, and creatinine are looked at.

Usually, the diagnosis of ADPKD is initially performed by renal imaging using ultrasound, CT scan, or MRI. However, molecular diagnostics can be necessary in the following situations: 1- when a definite diagnosis is required in young individuals, such as a potential living related donor in an affected family with equivocal imaging data; 2- in patients with a negative family history of ADPKD, because of potential phenotypic overlap with several other kidney cystic diseases; 3- in families affected by early-onset polycystic kidney disease, since in this cases hypomorphic alleles and/or oligogenic inheritance can be involved; and 4- in patients requesting genetic counseling, especially in couples wishing a pre-implantation genetic diagnosis.

The findings of large echogenic kidneys without distinct macroscopic cysts in an infant/child at 50% risk for ADPKD are diagnostic. In the absence of a family history of ADPKD, the presence of bilateral renal enlargement and cysts, with or without the presence of hepatic cysts, and the absence of other manifestations suggestive of a different renal cystic disease provide presumptive, but not definite, evidence for the diagnosis. In some cases, intracranial aneurysms can be an associated sign of ADPKD, and screening can be recommended for patients with a family history of intracranial aneurysm.

Molecular genetic testing by linkage analysis or direct mutation screening is clinically available; however, genetic heterogeneity is a significant complication to molecular genetic testing. Sometimes a relatively large number of affected family members need to be tested in order to establish which one of the two possible genes is responsible within each family. The large size and complexity of PKD1 and PKD2 genes, as well as marked allelic heterogeneity, present obstacles to molecular testing by direct DNA analysis. The sensitivity of testing is nearly 100% for all patients with ADPKD who are age 30 years or older and for younger patients with PKD1 mutations; these criteria are only 67% sensitive for patients with PKD2 mutations who are younger than age 30 years.

Guidelines for referral to a nephrologist vary between countries. Though most would agree that nephrology referral is required by Stage 4 CKD (when eGFR/1.73m is less than 30 ml/min; or decreasing by more than 3 ml/min/year); and may be useful at an earlier stage (e.g. CKD3) when urine albumin-to-creatinine ratio is more than 30 mg/mmol, when blood pressure is difficult to control, or when hematuria or other findings suggest either a primarily glomerular disorder or secondary disease amenable to specific treatment. Other benefits of early nephrology referral include proper patient education regarding options for renal replacement therapy as well as pre-emptive transplantation, and timely workup and placement of an arteriovenous fistula in those patients opting for future hemodialysis

The diagnosis of medullary cystic kidney disease can be done via a physical exam. Further tests/exams are as follows:

- A routine blood test called the serum creatinine can be done. Creatinine is a breakdown product from the muscle, as kidney function declines, the amount of blood creatinine goes up. Thus, most affected individuals have no symptoms of MCKD, but find that they have the condition due to an elevation in the blood creatinine level.

- Affected individuals also have an elevation in the blood uric acid level. In MCKD, the kidney has difficulty getting rid of uric acid. One can find out that the uric acid level in the blood is high when a blood test is done. Gout is caused by high uric acid levels, and thus patients often have gout.

- A kidney ultrasound in this condition usually shows normal or small sized kidneys (occasionally cysts are present). However, since cysts are present in many normal individuals, these cysts are not helpful in making a diagnosis, therefore a kidney biopsy can be done to determine if the individual has this disease. Kidney biopsy is a procedure where a needle is inserted into the kidney and removes a small piece of kidney tissue. This tissue is then examined under a microscope.

- Definitive testing and diagnosis of MCKD can be made by analyzing the UMOD gene for mutations, this can be done by a blood test.

Screening those who have neither symptoms nor risk factors for CKD is not recommended. Those who should be screened include: those with hypertension or history of cardiovascular disease, those with diabetes or marked obesity, those aged > 60 years, subjects with indigenous racial origin, those with a history of kidney disease in the past and subjects who have relatives who had kidney disease requiring dialysis. Screening should include calculation of estimated GFR from the serum creatinine level, and measurement of urine albumin-to-creatinine ratio (ACR) in a first-morning urine specimen (this reflects the amount of a protein called albumin in the urine), as well as a urine dipstick screen for hematuria. The GFR (glomerular filtration rate) is derived from the serum creatinine and is proportional to 1/creatinine, i.e. it is a reciprocal relationship (the higher the creatinine, the lower the GFR). It reflects one aspect of kidney function: how efficiently the glomeruli (filtering units) work. But as they make up <5% of the mass of the kidney, the GFR does not indicate all aspects of kidney health and function. This can be done by combining the GFR level with the clinical assessment of the patient (especially fluid state) and measuring the levels of hemoglobin, potassium, phosphate and parathyroid hormone (PTH). Normal GFR is 90-120 mLs/min. The units of creatinine vary from country to country.

Chronic kidney failure is measured in five stages, which are calculated using a patient’s GFR, or glomerular filtration rate. Stage 1 CKD is mildly diminished renal function, with few overt symptoms. Stages 2 and 3 need increasing levels of supportive care from their medical providers to slow and treat their renal dysfunction. Patients in stages 4 and 5 usually require preparation of the patient towards active treatment in order to survive. Stage 5 CKD is considered a severe illness and requires some form of renal replacement therapy (dialysis) or kidney transplant whenever feasible.

- Glomerular filtration rate

A normal GFR varies according to many factors, including sex, age, body size and ethnic background. Renal professionals consider the glomerular filtration rate (GFR) to be the best overall index of kidney function. The National Kidney Foundation offers an easy to use on-line GFR calculator for anyone who is interested in knowing their glomerular filtration rate. (A serum creatinine level, a simple blood test, is needed to use the calculator.)

Increasing fluid intake to yield a urine output of greater than 2 liters a day can be advantageous for all patients with nephrocalcinosis. Patients with hypercalciuria can reduce calcium excretion by restricting animal protein, limiting sodium intake to less than 100 meq a day and being lax of potassium intake. If changing ones diet alone does not result in an suitable reduction of hypercalciuria, a thiazide diuretic can be administered in patients who do not have hypercalcemia. Citrate can increase the solubility of calcium in urine and limit the development of nephrocalcinosis. Citrate is not given to patients who have urine pH equal to or greater than 7.

The deterioration of kidney function may be signaled by a measurable decrease in urine output. Often, it is diagnosed on the basis of blood tests for substances normally eliminated by the kidney: urea and creatinine. Additionally, the ratio of BUN to creatinine is used to evaluate kidney injury. Both tests have their disadvantages. For instance, it takes about 24 hours for the creatinine level to rise, even if both kidneys have ceased to function. A number of alternative markers has been proposed (such as NGAL, KIM-1, IL18 and cystatin C), but none of them is currently established enough to replace creatinine as a marker of kidney function.

Once the diagnosis of AKI is made, further testing is often required to determine the underlying cause. It is useful to perform a bladder scan or a post void residual to rule out urinary retention. In post void residual, a catheter is inserted into the urinary tract immediately after urinating to measure fluid still in the bladder. 50–100 ml suggests neurogenic bladder dysfunction.

These may include urine sediment analysis, renal ultrasound and/or kidney biopsy. Indications for kidney biopsy in the setting of AKI include the following:

1. Unexplained AKI, in a patient with two non-obstructed normal sized kidneys

2. AKI in the presence of the nephritic syndrome

3. Systemic disease associated with AKI

4. Kidney transplant dysfunction

In medical imaging, the acute changes in the kidney are often examined with renal ultrasonography as the first-line modality, where CT scan and magnetic resonance imaging (MRI) are used for the follow-up examinations and when US fails to demonstrate abnormalities. In evaluation of the acute changes in the kidney, the echogenicity of the renal structures, the delineation of the kidney, the renal vascularity, kidney size and focal abnormalities are observed. CT is preferred in renal traumas, but US is used for follow-up, especially in the patients suspected for the formation of urinomas. A CT scan of the abdomen will also demonstrate bladder distension or hydronephrosis. However, in AKI, the use of IV contrast is contraindicated as the contrast agent used is nephrotoxic.

Polycystic kidney disease can be ascertained via a CT scan of abdomen, as well as, an MRI and ultrasound of the same area. A physical exam/test can reveal enlarged liver, heart murmurs and elevated blood pressure

In ADPKD patients, gradual cyst development and expansion result in kidney enlargement, and during the course of the disease, glomerular filtration rate (GFR) remains normal for decades before kidney function starts to progressively deteriorate, making early prediction of renal outcome difficult. The CRISP study, mentioned in the treatment section above, contributed to build a strong rationale supporting the prognostic value of total kidney volume (TKV) in ADPKD; TKV (evaluated by MRI) increases steadily and a higher rate of kidney enlargement correlated with accelerated decline of GFR, while patient height-adjusted TKV (HtTKV) ≥600 ml/m predicts the development of stage 3 chronic kidney disease within 8 years.

Besides TKV and HtTKV, the estimated glomerular filtration rate (eGFR) has also been tentatively used to predict the progression of ADPKD. After the analysis of CT or MRI scans of 590 patients with ADPKD treated at the Mayo Translational Polycystic Kidney Disease Center, Irazabal and colleagues developed an imaging-based classification system to predict the rate of eGFR decline in patients with ADPKD. In this prognostic method, patients are divided into five subclasses of estimated kidney growth rates according to age-specific HtTKV ranges (1A, 6.0%) as delineated in the CRISP study. The decline in eGFR over the years following initial TKV measurement is significantly different between all five patient subclasses, with those in subclass 1E having the most rapid decline.

ADPKD individuals might have a normal life; conversely, ARPKD can cause kidney dysfunction and can lead to kidney failure by the age of 40-60. ADPKD1 and ADPKD2 are very different, in that ADPKD2 is much milder.

Currently, there are no therapies proven effective to prevent the progression of polycystic kidney disease (autosomal dominant).

Before the advancement of modern medicine, renal failure was often referred to as uremic poisoning. Uremia was the term for the contamination of the blood with urine. It is the presence of an excessive amount of urea in blood. Starting around 1847, this included reduced urine output, which was thought to be caused by the urine mixing with the blood instead of being voided through the urethra. The term "uremia" is now used for the illness accompanying kidney failure.

The "RIFLE criteria", proposed by the Acute Dialysis Quality Initiative (ADQI) group, aid in assessment of the severity of a person's acute kidney injury. The acronym RIFLE is used to define the spectrum of progressive kidney injury seen in AKI:

- Risk: 1.5-fold increase in the serum creatinine, or glomerular filtration rate (GFR) decrease by 25 percent, or urine output <0.5 mL/kg per hour for six hours.

- Injury: Two-fold increase in the serum creatinine, or GFR decrease by 50 percent, or urine output <0.5 mL/kg per hour for 12 hours

- Failure: Three-fold increase in the serum creatinine, or GFR decrease by 75 percent, or urine output of <0.3 mL/kg per hour for 24 hours, or no urine output (anuria) for 12 hours

- Loss: Complete loss of kidney function (e.g., need for renal replacement therapy) for more than four weeks

- End-stage kidney disease: Complete loss of kidney function (e.g., need for renal replacement therapy) for more than three months

The standard diagnostic workup of suspected kidney disease is history & examination, as well as a urine test strip. Also, renal ultrasonography is essential in the diagnosis and management of kidney-related diseases.

Individuals with renal papillary necrosis due to excess use of analgesic have an elevated risk of epithelial tumors, hence a urine cytology exam is useful. In terms of imaging this condition can be identified by retrograde pyelography (RGP). The diagnosis of renal papillary necrosis is therefore done via:

In terms of treatment/management for medullary cystic kidney disease, at present there are no specific therapies for this disease, and there are no specific diets known to slow progression of the disease. However, management for the symptoms can be dealt with as follows: erythropoietin is used to treat anemia, and growth hormone is used when growth becomes an issue. Additionally, a renal transplant may be needed at some point.

Finally, foods that contain potassium and phosphate must be reduced

Diagnosis is traditionally based on the clinical findings above in combination with excessive analgesic use. It is estimated that between 2 and 3 kg each of phenacetin or aspirin must be consumed before evidence of analgesic nephropathy becomes clinically apparent.

Once suspected, analgesic nephropathy can be confirmed with relative accuracy using computed tomography (CT) imaging without contrast. One trial demonstrated that the appearance of papillary calcifications on CT imaging was 92% sensitive and 100% specific for the diagnosis of analgesic nephropathy.

Complications of analgesic nephropathy include pyelonephritis and end-stage kidney disease. Risk factors for poor prognosis include recurrent urinary tract infection and persistently elevated blood pressure. Analgesic nephropathy also appears to increase the risk of developing cancers of the urinary system.

Treatment of renal papillary necrosis is supportive, any obstruction (urethral) can be dealt with via stenting. This condition is not linked to a higher possibility of renal failure. Control of infection is important, thus antimicrobial treatment is begun, so as to avert surgery (should the infection not respond).

Biochemical blood tests determine the amount of typical markers of renal function in the blood serum, for instance serum urea and serum creatinine. Biochemistry can also be used to determine serum electrolytes. Special biochemical tests (arterial blood gas) can determine the amount of dissolved gases in the blood, indicating if pH imbalances are acute or chronic.

Urinalysis is a test that studies urine for abnormal substances such as protein or signs of infection.

- A Full Ward Test, also known as dipstick urinalysis, involves the dipping of a biochemically active test strip into the urine specimen to determine levels of tell-tale chemicals in the urine.

- Urinalysis can also involve MC&S microscopy, culture and sensitivity

Urodynamic tests evaluate the storage of urine in the bladder and the flow of urine from the bladder through the urethra. It may be performed in cases of incontinence or neurological problems affecting the urinary tract.

Ultrasound is commonly performed to investigate problems of the kidney and/or urinary tract.

Radiology:

- KUB is plain radiography of the urinary system, e.g. to identify kidney stones.

- An intravenous pyelogram studies the shape of the urinary system.

- CAT scans and MRI can also be useful in localising urinary tract pathology.

- A voiding cystogram is a functional study where contrast "dye" is injected through a catheter into the bladder. Under x-ray the radiologist asks the patient to void (usually young children) and will watch the contrast exiting the body on the x-ray monitor. This examines the child's bladder and lower urinary tract. Typically looking for vesicoureteral reflux, involving urine backflow up into the kidneys.

Patients will require dialysis to compensate for the function of their kidneys.

Prompt treatment of some causes of azotemia can result in restoration of kidney function; delayed treatment may result in permanent loss of renal function. Treatment may include hemodialysis or peritoneal dialysis, medications to increase cardiac output and increase blood pressure, and the treatment of the condition that caused the azotemia.

Increase the water intake to prevent oxalates to precipitate .

Minimize dietary intake of oxalates by restricting the intake of leafy vegetables , sesame seeds , tea , cocoa , beet root , spinach , rhubarb , etc.

While the only diagnostic "gold standard" mechanism of diagnosis en vivo is via kidney biopsy, the clinical conditions and blood clotting disorder often associated with this disease may make it impractical in a clinical setting. Alternatively, it is diagnosed clinically, or at autopsy, with some authors suggesting diagnosis by contrast enhanced CT.

It is possible to analyze urine samples in determining albumin, hemoglobin and myoglobin with an optimized MEKC method.