Nephrology and Hypertension

Requisitions:

Please the Nephrology Laboratory Requisition Form when shipping samples. Special handling instructions are required for ADAMTS13 testing. Please complete the Clinical Information field on the Nephrology Laboratory Requisition for ADAMTS13 and Complement testing, if available.

Shipping:

 
Please ship samples frozen, on dry ice, overnight to:
Cincinnati Children’s Hospital Medical Center
Attention Lab Processing B-4
3333 Burnet Avenue
Cincinnati Ohio 45239-3039

Contact:

 
Specimen Pickup and Fax Network Inquiries:
For specimen pickups or to fax inquiries, call l 513-636-7328 or 1-800-653-5516.

To Obtain Lab Results (Professionals Only):
To obtain lab results, healthcare professionals can call 513-636-4281.

General Information:
For general information about clinical laboratories services at Cincinnati Children’s, contact 513-636-7355.
The Nephrology Clinical laboratory may be reached at (513) 636-4530.

Clinical Laboratories Email Address:
The clinical laboratories at Cincinnati Children’s now have an email address for non-urgent questions or concerns. A response will be sent within one business day. Medical advice or lab test result interpretation cannot be offered. Send general questions, comments or concerns to: AskTheLab.

Test may be ordered as single tests. Many of the tests are available as a profile to aid in the diagnosis of specific disease states. Click on the tabs for additional information.

(ATS13, ATS13 INHIB, ATS13 AB)

ADAMTS13 activity, ADAMTS13 inhibition test, ADAMTS13 antibody level

The Nephrology Clinical Lab and the Center for Acute Care Nephrology at Cincinnati Children’s Hospital Medical Center are pleased to announce the on-site availability of a complete ADAMTS13 panel (ADAMTS13 Activity assay, ADAMTS13 Inhibition Test and ADAMTS13 Inhibitor Antibody testing).

ADAMTS13, a serum protease that cleaves multimers of von Willebrand Factor into smaller oligomeric fragments. ADAMTS13 activity is severely reduced in acquired and congenital forms of thrombotic thrombocytopenic purpura (TTP), leading to very large circulating multimers of von Willebrand Factor, and may be moderately reduced in other conditions such as disseminated intravascular coagulation, sepsis, hepatic dysfunction, and pregnancy.  Assessment of ADAMTS13 activity is an important component of the initial assessment of a patient with evidence for a thrombotic microangiopathy such as atypical hemolytic uremic syndrome (aHUS) and TTP, suggesting atypical hemolytic uremic syndrome if ADAMTS13 activity is normal or moderately reduced, and TTP if ADAMTS13 activity is severely reduced.

ADAMTS13 testing will be offered in a reflex testing algorithm, in which the Inhibition Test and Inhibitor Antibody testing will only be performed if the activity is <30% (most acquired and congenital forms of TTP demonstrate <10% ADAMTS13 activity).  If activity is <30%, the Inhibition Test will be performed automatically.  If the Inhibition Test demonstrates >30% inhibition of the activity of normal plasma, the Inhibitor Antibody testing will be performed to detect an autoantibody which inhibits ADAMTS13 activity. Each of these tests are also orderable individually. All results will be interpreted by a nephrologist.

Each of the three tests in the panel requires 0.5mL of plasma (total of 1.5mL plasma or 3mL blood), and must be sent in a citrated (blue top) tube.  The tests are listed in  as ADAMTS13 Activity, ADAMTS13 Inhibition Test, and ADAMTS13 Inhibitor Antibody.  Turnaround time for this assay has improved from up to two weeks previously to 24 hours during weekdays, to enhance the ability to make the diagnosis of TTP quickly and allow more rapid and appropriate intervention with definitive therapy, specifically plasmapheresis.

• Nephrology Laboratory Requisition Form
• ADAMTS13 Testing Algorithm
• ADAMTS13 Testing in the Diagnosis of Thrombotic Thrombocytopenic Purpura
• Sample Collection and Preparation for Platelet-Poor Plasma

aHUS / TTP (TMA) Profile

Thrombotic microangiopathy (TMA) is a category of diseases linked by a common pathomechanism of endothelial injury leading to microvascular thrombosis and fibrin deposition, aggregation of platelets on the damaged endothelium, and organ dysfunction related to microvascular injury.  This category includes Shiga toxin-producing E. coli associated hemolytic uremic syndrome (STEC-HUS), atypical hemolytic uremic syndrome (aHUS), and thrombotic thrombocytopenic purpura (TTP), among others.  Atypical HUS is associated with defects in the regulation of the alternative complement pathway leading to uninhibited formation of the C3 convertase C3bBb on the endothelium and subsequent microvascular injury, whereas TTP is caused by the inability of ADAMTS13 to cleave ultra large multimers of von Willebrand Factor (vWF), with resulting adhesion of these ultra large vWF multimers to the endothelial surface under shear stress leading to microvascular thrombosis and injury. The evaluation of thrombotic microangiopathy includes testing the regulatory components of the alternative complement pathway for aHUS and the activity of ADAMTS13.  The TMA Profile performed by the Nephrology Clinical Laboratory at CCHMC tests the quantitative levels of C3, C4, Factor H, Factor I, Factor B; ADAMTS13 activity, and autoantibody against Factor H.

Cystatin C measurements are used in the diagnosis and treatment of renal diseases. A calculated GFR is reported with the Cystatin C concentration.

Is a cysteine proteinase inhibitor and is formed by all nucleated cells.  As it is formed at a constant rate and freely filtered by the healthy kidney it can be used for assessing renal function. Serum concentrations of Cystatin C are almost totally dependent on the glomerular filtration rate. A reduction in the GFR results in a rise in the concentration of Cystatin C. Cystatin C has not been shown to be affected by factors such as muscle mass and nutrition, factors which have been demonstrated to affect creatinine values. In addition, a rise in creatinine does not become evident until the GFR has fallen by approximately 50%.

A GFR is calculated from the Cystatin C concentration and is reported with the Cystatin C result. 

Specimen requirements are 1 ml of fresh serum or plasma, stored frozen.  

Note: Tests can be performed individually, or in a profile package.

 

C1Q	C5	C9	Properdin
C2	C6	Factor H	C4 Binding Protein
C3	C7	Factor I	C1 Inhibitor
C4	C8	Factor B	Nephritic Factor (optional)

 

This profile is useful in the detection of inherited complement deficiencies that may predispose to lupus-like syndromes, to recurrent bacterial infection, particularly Neisserial, or to hereditary angioedema. In association with the measurement of nephritic factor, this profile aids in distinguishing acute from chronic nephritis and in identifying the three types of membranoproliferative glomerulonephritis. A nephrologist interprets all Complete Complement Profiles.

Specimen requirements 1 ml serum, frozen.

The SPP is useful in diagnosing dysgammaglobulinemias, iron deficiency, idiopathic nephrotic syndrome of childhood, active systemic lupus erythematosus and hypocomplementemic glomerulonephritides. The profile also aids in the assessment of the status of the immune system in patients receiving chemotherapy and may be abnormal in the presence of viral infections, the IgA nephropathies and acute and chronic inflammation. A nephrologist interprets all SPPs.

IgG Subclasses (IGG SBCLAS)

Total lgG 1, lgG 2, lgG 3, lgG 4.

A nephelometric measurement of the four IgG subclasses, deficiencies of which can be associated with recurrent infection, particularly of the respiratory tract. A nephrologist interprets all IgG subclasses.

Specimen requirements: 1 mL serum, frozen.

Antistreptolysin O Antibody (ASO)

An elevated level of ASO is suggestive of a recent streptococcal infection. The test has low specificity in that 25-30 percent of normal children have elevated levels.

Specimen requirements 1 mL serum, frozen.

Rheumatoid factors are antibodies which are directed against the Fc fragment of IgG altered in its tertiary structure. They occur in all immunoglobulin classes; the RF isotypes are identified as IgM-, IgG-, and IgA rheumatoid factors. The presence or absence of rheumatoid factors has high diagnostic power in confirming or ruling out preliminary diagnoses developed from patient history and clinical findings.

Specimen requirements 1 mL serum, frozen.

This assay is intended for the quantitative detection of IgG antibodies directed against human complement factor H in human serum or plasma. 

Factor H is a complement regulatory glycoprotein that is found in human plasma in concentrations of about 50 mg/dl.  Its main function is to bind to C3b deposited on the surface of endothelial cells and facilitate its cleavage to an inactive form, iC3b, by another complement regulatory protein, factor I.  Failure to facilitate this cleavage by defects in the regulatory components of the alternative complement pathway may lead to unregulated formation of the C3 convertase C3bBb on the surface of the cell, and ultimately unregulated formation of the membrane attack complex C5b-9 on the cell surface leading to cell lysis.  Inhibitory autoantibodies directed against complement factor H may therefore dysregulate the alternative pathway of the complement system.  Such autoimmune dysregulation of the alternative complement pathway has been identified in ~5% of patients with atypical hemolytic uremic syndrome (aHUS), and has also been identified in patients with membranoproliferative glomerulonephritis (MPGN).  Removal of anti-factor H antibodies from the bloodstream by plasmapheresis or the use of immunosuppressive drugs to eliminate the autoantibody production has shown benefit in the outcome of these diseases.

Specimen requirement 1ml serum or plasma frozen

C3 Nephritic Factor (C3 NEF)

An autoantibody that depresses the serum level of C3 and, secondarily, other complement components. Among the hypocomplementemic glomerulonephritides, nephritic factor is absent in acute post-streptococcal glomerulonephritis and lupus nephritis. It is present in most hypocomplementemic patients with membranoproliferative glomerulonephritis and also those with partial lipodystrophy. Although the antibody may be instrumental in producing the nephritis, its level is not closely associated with the clinical course.

Specimen requirements 1 mL serum, frozen.

Hereditary Angioneurotic Edema (Hane) Profile (HANE PROF)

C1 Inhibitor

C2

C3

C4

 

This profile distinguishes HANE from other urticarias. A nephrologist interprets all Hane profiles.

Specimen requirements: 1 mL serum, frozen.

Nutritional Complement Profile (NUTRIT PRO)

Factor B

Factor H

Factor I

C3

 

For distinguishing low levels of C3 resulting from undernutrition from those due to complement activation. A nephrologist interprets all Nutritional Complement Profiles.

Specimen requirements 1 mL serum, frozen.

A child requiring this test is found to have protein in the urine, a condition known as proteinuria. Sometimes this is a sign of serious kidney disease. Other times, however, this is a normal finding that seems to be related to body position. Protein in the urine caused by the upright position is called postulatory or orthostatic proteinuria, and is not serious. The test is performed in order to establish if the protein in a child’s urine is caused by the upright position.

Click here for instructions on collecting a urine protein sample.