Creatinine, Urine

Laboratory assay overview

The primary hyperoxalurias (PH) are a group of inherited disorders caused by defects in glyoxylate metabolism, with a combined incidence of about 1:60,000. To date, three primary hyperoxaluria have been described, designated as PH1, PH2, and PH3. All three forms follow an autosomal recessive mode of inheritance, and lead to increased oxalate levels in the body. The typical presentation is with recurring calcium oxalate renal stones. Calcium oxalate can also deposit in various tissues including the kidneys (nephrocalcinosis). End stage renal disease can occur from damage caused by the systemic oxalosis. The age of onset of symptoms ranges from infancy to adulthood; some adults may remain asymptomatic until the sixth decade.

Laboratory assay overview

Values above 10 mg/24 hrs occur in carcinoid syndrome. Slight elevations also occur in nontropical sprue and after reserpine administration. Drugs which can interfere with testing due to physiologic response: Acetaminophen, Alpha and Beta Blockers, Atenolol, Bromocriptine, Bronchodilators, Clonidine, Digoxin, Isoniazid, L-Dopa, Labetalol, Methyldopa, Monoamine Oxidase Inhibitors, Nitroglycerin, Sympathomimetic Amines, Phenobarbital, Phenothiazines, Phentolamine, Reserpine, Salicylates, Tricyclic Antidepressants

Laboratory assay overview

A serotonin analysis is most frequently performed for the diagnosis of carcinoid tumors of the enterochromaffin (Kultschitzsky) cells of the small intestine. These tumor cells release large amounts of serotonin, which can produce the clinical syndrome of flushing, diarrhea, and right-sided heart failure. The most frequently used diagnostic test for carcinoid tumors is 5-HIAA, the final metabolite of serotonin. Diagnose carcinoid tumors and syndrome; values >25 mg/24 hours (higher if the patient has malabsorption) are strong evidence for carcinoid.

Laboratory assay overview

This test is used to detect albuminuria by measuring albumin and creatine concentrations in a random (spot) urine sample and calculating the albumin-creatinine ratio (ACR). This test is useful for assessing kidney damage, especially at an early stage, and informing management and prognosis of chronic kidney disease (CKD) [1]. Albuminuria, as a marker of kidney damage, provides a more specific and sensitive measurement of glomerular permeability than does proteinuria. An ACR measured from a spot urine sample acquired in the early morning is preferred for initial evaluation of albuminuria. This test can also be used to confirm a positive reagent strip urinalysis result. A moderately increased ACR (≥30 mg/g) for more than 3 months is diagnostic of CKD. The severity of albuminuria is also used for staging and prognosis of CKD [1,2]. Albuminuria generally appears before the reduction of glomerular filtration rate in people with diabetic glomerulosclerosis but may appear later in people with hypertensive nephrosclerosis. Albuminuria is independently associated with an increased risk of cardiovascular events and mortality. In individuals with diabetes and/or hypertension, early identification of albuminuria that prompts blood pressure and glycemic control may subsequently reduce the risk of cardiovascular events and CKD progressing to end-stage renal disease. Referral to specialist kidney care services is recommended in individuals with a consistent finding of severely increased ACR (≥300 mg/g) [1-4]. Factors that affect urinary ACR include menstrual blood contamination, symptomatic urinary tract infections, exercise, upright posture (orthostatic proteinuria), and other conditions that increase vascular permeability (eg, septicemia). Given the pathological and physiological causes of transient albuminuria, repeating ACR tests twice with early morning urine samples in the next 2 months is recommended. ACR from a timed urine sample can provide a more accurate estimate of albuminuria [1]. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. References 1. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int Suppl. 2013;3(1):1-150. 2. Inker LA, et al. Am J Kidney Dis. 2014;63(5):713-735. 3. American Diabetes Association. Standards of medical care in diabetes-2020. Diabetes Care. 2020;43(suppl 1):S135-S151. 4. Shin JI, et al. Hypertension. 2021;78(4):1042-1052.

Laboratory assay overview

This test is used for measurement of albumin levels in urine below the detection level of urine dipsticks. This test is useful in the management of patients with relatively early diabetes mellitus to assist in avoiding or delaying the onset of diabetic renal disease.

Laboratory assay overview

Monitor patients for prior and ongoing exposure to aluminum. Patients at risk include: • Infants on parenteral fluids, particularly parenteral nutrition • Burn patients through administration of intravenous albumin, particularly with coexisting renal failure • Adult and pediatric patients with chronic renal failure who accumulate aluminum readily from medications and dialysate • Adult parenteral nutrition patients (less so, recently) • Patients with industrial exposure Monitor dialysate and water to prepare dialysate to prevent aluminum toxicity in dialysis patients.

Laboratory assay overview

Urinary amylase is useful in the consideration of macroamylasemia and pseudocyst of the pancreas. With macroamylasemia, only the serum concentration is elevated. With pseudocysts, the urinary concentration remains elevated for weeks after an episode of acute pancreatitis.

Quest Diagnostics population reference ranges

Quest Diagnostics calculates these statistical intervals for this specific assay and demographic group, not as universal optimal targets.

Laboratory assay overview

Exposure monitoring/Investigation.

Laboratory assay overview

Overexposure/poisoning determination.

Laboratory assay overview

Monitor chronic exposure to arsenic

Laboratory assay overview

Arsenic is widely distributed in the earth's crust. Arsenic is used in some pesticides and industrial applications. Arsenic toxicity can cause skin changes, respiratory illness, nausea and vomiting, and other effects.

Laboratory assay overview

Aspirin (which inhibits platelet cyclooxygenase) reduces the risk of thrombosis in cardiovascular disease by impairing platelet function. Patients who do not respond to the platelet inhibitory effects of aspirin are designated as "aspirin resistant". The measurement of 11-dhTXB2 in urine (the principal metabolite of platelet cyclooxygenase derived thromboxane B2) may be used in individuals with cardiovascular disease prior to initiation of aspirin therapy, or in individuals non-responsive to aspirin therapy.

Laboratory assay overview

Beryllium is used as a neutron modulator in nuclear reactors and inertial systems. It can also be found in the manufacturing of electronic and radio tubes, electric heating elements and x-ray tube windows. Beryllium is a component of radar devices, nose cones, jet plane brakes and missiles. It is highly toxic with death resulting from very short exposure to low concentrations of the element or its salts. Symptoms include dermatitis, corneal burns, non-healing ulcerations, vomiting, cyanosis and nausea.

Laboratory assay overview

Beta-2 Microglobulin (B2M) is a low molecular weight protein that forms the light chain component of the histocompatibility antigen. It is synthesized by all nucleated cell types. It is an integral part of the class I MHC antigens and is present in all body fluids. B2M is filtered through the glomeruli of the kidney and is then reabsorbed and catabolized by the proximal tubular cells. In normal patients only trace amounts of B2M appear in the urine. Elevated urine B2M is seen in tubulo-interstitial disorders. Increased urine B2M is seen in cadmium exposure, diatrizoate, exercise, fever, nephrectomy, semen. There is evidence that monitoring B2M levels in HIV-infected individuals offers an independent predictor of progression to AIDS, leukemia and lymphoma.

Laboratory assay overview

Excessive use of Bismuth containing medications may cause renal damage and other adverse effects.

Laboratory assay overview

This test is used to detect and confirm the presence of prescribed and illicit drugs for monitoring Suboxone™/buprenorphine medication assisted treatment (MAT). Please note this testing is designed specifically for monitoring patients who are on Suboxone™/buprenorphine only. This testing should not be used for monitoring chronic pain patients (medical drug monitoring) or methadone medication assisted treatment.

Laboratory assay overview

This test is used to detect and confirm presence of prescribed and illicit drugs for monitoring Suboxone™/buprenorphine medication assisted treatment (MAT). Please note this testing is designed specifically for monitoring patients who are on Suboxone™/buprenorphine only. This testing should not be used for monitoring chronic pain patients (medical drug monitoring) or methadone medication assisted treatment.

Laboratory assay overview

This test is used to detect and confirm presence of prescribed and illicit drugs for monitoring Suboxone™/buprenorphine medication assisted treatment (MAT). Please note this testing is designed specifically for monitoring patients who are on Suboxone™/buprenorphine only. This testing should not be used for monitoring chronic pain patients (medical drug monitoring) or methadone medication assisted treatment.

Laboratory assay overview

See individual tests.

Laboratory assay overview

Cadmium is a naturally occurring element that is mined and used in industrial production because of its durability. Excessive cadmium exposure can damage lungs, kidneys, and the digestive tract.

Laboratory assay overview

Monitor exposure to cadmium

Laboratory assay overview

This quantitative test, performed with a random pediatric urine specimen, may help screen for hypercalciuria, one of the established risk factors for kidney stone formation [1-3]. This test may also help assess metabolic disorders of calcium metabolism, such as hyperparathyroidism, bone disease, and idiopathic hypercalciuria. To adjust for the concentration differences in random urine specimens, calcium to creatinine ratio is included in the results. In general, 24-hour urine specimens are preferred to random urine specimens when measuring calcium for diagnostic evaluation of hypercalciuria [1]. Calcium is essential for bone formation and nerve, muscle, and heart functions. Calcium metabolism is jointly regulated by parathyroid hormone and vitamin D metabolites. Urinary calcium excretion is the major route of calcium elimination and reflects kidney tubular filtration and reabsorption of calcium in addition to dietary intake, intestinal absorption, and bone resorption [2]. Urinary calcium levels may be elevated in patients with idiopathic hypercalciuria, chronic kidney disease, hyperparathyroidism, vitamin D intoxication, Paget disease of bone, sarcoidosis, or conditions that infiltrate and destroy bones (eg, multiple myeloma and a variety of metastatic cancers) [2,3]. Urinary calcium levels may be decreased in patients with hypoparathyroidism, vitamin D deficiency rickets, osteomalacia, or familial hypocalciuric hypercalcemia [2,3]. Note that use of calcium supplements and loop diuretics may cause increased urinary calcium levels; thiazide diuretics may cause decreased urinary calcium levels [3]. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. References 1. Williams JC Jr, et al. Urolithiasis. 2021;49(1):1-16. 2. Rifai N, et al. eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elservier Inc; 2022 3. MedlinePlus [Internet]. Calcium-urine. Accessed September 1, 2022. https://medlineplus.gov/ency/article/003603.htm

Laboratory assay overview

This quantitative test, performed with a random urine specimen, may help screen for hypercalciuria, one of the established risk factors for kidney stone formation [1-3]. This test may also help assess metabolic disorders of calcium metabolism, such as hyperparathyroidism, bone disease, and idiopathic hypercalciuria. To adjust for the concentration differences in random urine specimens, calcium to creatinine ratio is included in the results. In general, 24-hour urine specimens are preferred to random urine specimens when measuring calcium for diagnostic evaluation of hypercalciuria [1]. Calcium is essential for bone formation and nerve, muscle, and heart functions. Calcium metabolism is jointly regulated by parathyroid hormone and vitamin D metabolites. Urinary calcium excretion is the major route of calcium elimination and reflects kidney tubular filtration and reabsorption of calcium in addition to dietary intake, intestinal absorption, and bone resorption [2]. Urinary calcium levels may be elevated in patients with idiopathic hypercalciuria, chronic kidney disease, hyperparathyroidism, vitamin D intoxication, Paget disease of bone, sarcoidosis, or conditions that infiltrate and destroy bones (eg, multiple myeloma and a variety of metastatic cancers) [2,3]. Urinary calcium levels may be decreased in patients with hypoparathyroidism, vitamin D deficiency rickets, osteomalacia, or familial hypocalciuric hypercalcemia [2,3]. Note that use of calcium supplements and loop diuretics may cause increased urinary calcium levels; thiazide diuretics may cause decreased urinary calcium levels [3]. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. References 1. Williams JC Jr, et al. Urolithiasis. 2021;49(1):1-16. 2. Rifai N, et al. eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elservier Inc; 2022 3. MedlinePlus [Internet]. Calcium-urine. Accessed September 1, 2022. https://medlineplus.gov/ency/article/003603.htm

Laboratory assay overview

A random urine calcium:creatinine ratio is used to screen for hypercalciuria, as it is found to have a good correlation with 24-hour urine calcium excretion.1 Increased urinary excretion of calcium accompanies hyperparathyroidism, vitamin D intoxication, diseases that destroy bone (such as multiple myeloma), metastasis from prostatic cancer, and following calcium supplementation. Urine calcium is increased with immobilization, with steroid therapy, with Paget disease, and in primary (idiopathic) hypercalciuria.

Laboratory assay overview

According to the National Kidney Foundation, there are approximately 37 million adults in the U.S. who have chronic kidney disease (CKD), and about 90% are unaware of their condition. Diabetes is the leading cause of CKD in the United States. The significant impact of CKD on cardiovascular disease (CVD) risk has been increasingly recognized. Patients with CKD are far more likely to die, predominantly from CVD, than to progress to end-stage renal disease (ESRD). Currently, mainstays of treatment for diabetic kidney disease include control of hypertension, hyperglycemia and dyslipidemia. This panel has been established to aid in the identification and monitoring of hyperglycemia, dyslipidemia and CKD in patients with a history of diabetes and/or kidney disease. Guidelines and expert panels advocate renal function testing patients with diabetes and/or hypertension at least annually with urinary albumin to creatinine ratio (uACR) and estimated glomerular filtration rate (eGFR). CKD is characterized by gradual loss of kidney function over time, defined as presence of either kidney damage (as indicated by the presence of albuminuria) or declining kidney function (as indicated by the level of GFR) for more than three months.1 Non-HDL-C is a calculation (total cholesterol minus HDL-C), and includes the sum of the VLDL-C, LDL-C, and IDL-C. While LDL-C has long been the primary focus of cholesterol reduction efforts, there are several other lipoproteins that also affect cardiovascular health. The advantage of non-HDL-C measurement is that it accounts for cholesterol in the other potentially atherogenic lipoprotein particles, which include VLDL-C, IDL-C, LDL-C, and lipoprotein(a). Recent guidelines suggest that non-HDL levels above 190 mg/dL enhances the risk for CVD.2 Hemoglobin A1c values are used to assess glucose control in diabetes, and in 2010, the American Diabetes Associations affirmed the decision of an international expert committee recommendation to use the A1c test to diagnose diabetes with a threshold ≥6.5%. The Cardiorenal-glycemic Panel can be collected non-fasting.

Laboratory assay overview

This panel may aid in evaluating catecholamine-producing pheochromocytomas and paragangliomas (PPGLs). However, measurements of plasma free or urinary fractionated metanephrines (ie, the O-methylated catecholamine metabolites) are preferred for the initial biochemical evaluation of PPGLs because of their overall high diagnostic sensitivity [1]. To adjust for the concentration differences in random urine specimens, results are expressed as catecholamine to creatinine ratios. Most PPGLs secrete catecholamines and can cause catecholamine excess, resulting in hypertension, arrhythmia, and hyperglycemia. Left untreated, PPGLs often lead to life-threatening cardiovascular complications. The estimated prevalence of PPGLs is 0.05% to 0.1% in adults with hypertension and 1.7% in children with hypertension [2]. Recognizing the possibility of a PPGL and performing appropriate biochemical testing are crucial for the diagnosis [1]. Plasma or urine catecholamine levels may be used, in addition to metanephrine levels, to provide additional information during the initial biochemical evaluation of PPGLs (eg, when detecting dopamine-secreting paragangliomas) [2]. Intermittent or insignificant secretion of catecholamines by some PPGLs may not increase catecholamine measurements. Physiological stress and certain medications (eg, acetaminophen, labetalol, and sotalol) may increase catecholamine measurements [1]. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. ⁠⁠⁠⁠⁠⁠⁠References 1. Lenders JW, et al. J Clin Endocrinol Metab. 2014;99(6):1915-1942. 2. National Comprehensive Cancer Network. NCCN clinical practice guidelines in oncology (NCCN Guidelines®). Neuroendocrine and Adrenal Tumors. V1.2022. Accessed June 28, 2022. http://www.nccn.org

Laboratory assay overview

Work up neuroblastoma; diagnose pheochromocytoma. Pheochromocytomas and occasional paragangliomas may cause persistent or paroxysmal hypertension. Work up palpitation, severe headache, diaphoresis. Evaluate for possible multiple endocrine adenomatosis type II.

Laboratory assay overview

Urine chloride excretion approximates the dietary intake. The chloride content of most foods parallel that of sodium. An increase in urine chloride may result from water deficient dehydration, diabetic acidosis, Addison's Disease, and salt-losing renal disease. Decreased urine levels are seen in congestive heart failure, severe diaphoresis and in hypochloremic metabolic alkalosis due to prolonged vomiting.

Laboratory assay overview

Monitor industrial exposure to chromium

Laboratory assay overview

Occupational exposure and exposure to environmental contamination of chromium may lead to toxicity. The need of chromium supplements is unproven. Supplements taken in excess can lead to toxicity.

Laboratory assay overview

A timed 24-hour urine collection is the preferred specimen for measuring and interpreting this urinary analyte. Random collections normalized to urinary creatinine may be of some clinical use in patients who cannot collect a 24-hour specimen, typically small children. The mean urinary citrate excretion rate in patients with idiopathic calcium urolithiasis has been found to be significantly lower than that of control groups. Hypocitraturia is common in patients with urolithiasis resulting from renal tubular acidosis and in patients with enteric hyperoxaluria. Citrate excretion is low in renal insufficiency.

Laboratory assay overview

This quantitative citric acid test, performed with a random urine specimen, may help assess the risk of calcium stone formation in the kidneys and inform patient management [1]. In general, 24-hour urine specimens (Citric Acid, 24-Hour Urine with Creatinine) are preferred to random urine specimens when measuring citric acid for diagnostic evaluation and monitoring of calcium nephrolithiasis [2]. Citrate inhibits calcium stone formation by binding and solubilizing calcium, which reduces supersaturation of calcium salts [1-2]. Approximately half of the patients with calcium stones have decreased urinary citrate levels [1]. Citrate is among several substances routinely screened to evaluate the risk of forming kidney stones. Low urinary citrate levels may indicate oral citrate treatment in patients with recurrent calcium nephrolithiasis [1]. Other conditions that can cause hypocitraturia include distal renal tubular acidosis, malabsorption, and urinary tract infection [1]. The urinary citric acid level cannot be used to estimate dietary intake because other factors, such as acid-base balance, may affect citrate excretion [2]. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. ⁠⁠⁠⁠⁠⁠⁠References 1. Delaney, PM et al. Kidney disease. In: Rifai R, et al. eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier Inc; 2022. 2. Williams JC Jr, et al. Urolithiasis. 2021;49(1):1-16.

Laboratory assay overview

Monitor industrial exposure to cobalt

Laboratory assay overview

NTx is useful to assess bone resorption in patients with metabolic bone disease. The test is also useful in monitoring therapy to slow or halt osteoporotic bone loss. A decline of 30% or more of NTx over a six-month period suggests effective therapy.

Quest Diagnostics population reference ranges

Quest Diagnostics calculates these statistical intervals for this specific assay and demographic group, not as universal optimal targets.

Laboratory assay overview

Monitor exposure to arsenic, cadmium, chromium, cobalt, copper, lead, mercury and nickel

Laboratory assay overview

Monitor exposure to copper

Laboratory assay overview

Copper is an essential element that is a cofactor of many enzymes. Copper metabolism is disturbed in Wilson's disease, Menkes disease, primary biliary cirrhosis, and Indian childhood cirrhosis. Urinary copper concentrations are also useful to monitor patients on chelation therapy.

Quest Diagnostics population reference ranges

Quest Diagnostics calculates these statistical intervals for this specific assay and demographic group, not as universal optimal targets.

Laboratory assay overview

Monitor exposure to copper

Laboratory assay overview

Urinary free cortisol is useful in the detection of patients with Cushing's syndrome for whom free cortisol concentrations are elevated.

Laboratory assay overview

Renal function test; estimate glomerular filtration rate (GFR); evaluate renal function in small or wasted subjects; follow possible progression of renal disease; adjust dosages of medications in which renal excretion is pivotal (eg, aminoglycosides, methotrexate, cisplatin)

Laboratory assay overview

Renal function test when used as part of creatinine clearance; crude marker for completeness of 24-hour urine collections when collected for other purposes

Laboratory assay overview

The Dpd test can be used as a tool to assess bone resorption rates in healthy individuals and in patients with enhanced risk of developing metabolic bone disease. Significantly high levels of Dpd are found in children, in postmenopausal women due to estrogen deficiency, and in patients with diseases that have high bone turnover rates. Dpd can be used to monitor antiresorptive therapies in postmenopausal women and in individuals diagnosed with osteoporosis.

Laboratory assay overview

Monitor response to antiresorptive therapy in postmenopausal women and individuals with osteoporosis. Does not replace bone mineral density (BMD) screening to diagnose osteoporosis.

Laboratory assay overview

This test is intended to help inform the clinician about the presence of hyperlipidemia as an index to cardiovascular disease and to identify patients with chronic kidney disease.

Laboratory assay overview

This test is used to detect the presence of prescribed, over-the-counter and illicit drugs for the purpose of medical drug monitoring.

Laboratory assay overview

This test is used to detect the presence of prescribed and illicit drugs for monitoring treatment of substance use disorder, including medication assisted treatment (MAT).

Laboratory assay overview

An estimated 37 million U.S. adults have chronic kidney disease (CKD). In addition to cardiovascular-associated events, they are at risk for kidney failure or end-stage kidney disease (ESKD) requiring dialysis or kidney transplant. In the 2015-2016 National Health and Nutrition Examination Survey, prevalence of CKD stages G1-4 was 14.2% among adult participants. One in three U.S. adults is at risk for CKD due to prevalent risk factors such as diabetes and/or high blood pressure. The incidence of CKD is projected to increase during the next 20 years because of increasing obesity rates and an aging U.S. population.1 Early-stage CKD is often asymptomatic, making laboratory testing imperative for at-risk patients.This typically includes two tests, a serum creatinine with estimated glomerular filtration rate (eGFR), a test of kidney function, and a urine albumin-to-creatinine ratio (uACR), a test of kidney damage. While eGFR results are commonly reported as part of metabolic panels, this test alone is insufficient for CKD detection: The presence of albuminuria reflects endothelial inflammation that may cause proximal tubular damage and progressive kidney function loss.1 Asymptomatic individuals with diabetes, hypertension, family history of kidney disease and cardiovascular disease are considered to be at high risk for CKD and should be tested at least annually for eGFR and albuminuria.2 Additionally, total urine protein measurements may be warranted in some individuals to detect other etiologies of CKD missed by urine albumin measurements.3 The Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guidelines suggest measurement of cystatin C, an alternative endogenous filtration marker, in specific circumstances when GFR estimates based on serum creatinine are thought to be less accurate and when decisions depend on more accurate knowledge of GFR, such as confirmation of CKD diagnosis, determining eligibility for transplant or adjusting dosage of drugs excreted by the kidney.4 A 2021 report from the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Diseases recommended increased, routine and timely use of cystatin C combined with creatinine as a confirmatory assessment of kidney function, because combining filtration markers (creatinine and cystatin C) for eGFR calculation is more accurate and would support better clinical decisions than either marker alone. A new eGFR equation, the CKD-EPI 2021 eGFR creatinine-cystatin C equation without a race variable, was recommended for clinical use.5,6 More recently, the Chronic Kidney Disease Prognosis Consortium reported that the use of the new eGFR creatinine-cystatin C equation had significantly greater discrimination of risk of kidney failure with replacement therapy compared to creatinine only based eGFR equations, supporting the Task Force recommendations to increase cystatin testing.7