Total protein urine

The total proteins in the urine of patients with various lymphomas was higher than in normals. The reason for this was most likely an increased excretion of light chain proteins due to abnormal immunoglobulin synthesis. Most of these patients have secondaries in the kidneys, and this may well be a cause and effect phenomenon. 

Problems of traceability of total protein and catecholamine determinations in human urine... 

The Czech Reference Material CZ 6007a for total protein and creatinine in human urine was prepared [2], and served as a preliminary batch for the preparation of a certified reference material (CRM) for the stress indicators adrenaline (A), noradrenaline (NA) and dopamine(DA)in human urine. Some major problems in the traceability of these different analytes are presented. 

Fig. 1 Impact of sodium azide (NaN3 1 mg/ml) on total protein concentration in urine determined by the Lowry method...

Several kinds of traceability problems occurred during the preparation of CRM CZ 6007a Total Protein and Creatinine in Human Urine. 

A reference material (RM) for traceability of total protein in human urine does not exist. The control materials used in clinical laboratories for calibration purposes are not unified. Some laboratories use bovine serum albumin as a calibration material (URINE-CHIMIE BIOTROL) [5], whereas others use a mixture of human serum albumin (70%) and globulin (30%) (LYPHOCHECK Quantitative Urine Control, BIO-RAD) [6]. The use of various protein calibration standards yields various results of... 

Table 1 Six methods for the determination of total protein concentration in human urine were compared the Lowry method, biuret method, methods using the dyes Commassie Brilliant Blue (G250), Ponceau-S, pyrogallol red and the turbidity method by Exton...

The values of total protein and A concentrations in human urine are method-dependent. It is necessary to... 

Vitamin D-binding protein and its associated vitamin are lost in nephrotic urine. Biochemical abnormalities in nephrotic patients (children and adults) include hypocalcemia, both total (protein-bound) and ionized hypocalciuria, reduced intestinal calcium absorption and negative calcium balance reduced plasma 25-hydroxycholecalciferol and 24,25-dihydroxycholecalciferol and, surprisingly, also 1,25-dihydroxycholecalciferol and blunted response to parathormon (PTH) administration and increased PTH levels. Clinically, both osteomalacia and hyperparathyroidism have been described in nephrotic patients, more commonly in children than in adults, but bone biopsies are commonly normal, and clinically significant bone disease is very rare in nephrotic subjects. There is, however, evidence that patients with renal failure accompanied by nephrotic range proteinuria may be particularly prone to develop renal osteodystrophy. 

Twenty-four hour urine collection is preferred for best accuracy, although point-in-time samples can be used. Urine samples are collected from the species in question by appropriate methods (see section Assessment of Renal Injury by Urinalysis ). Total protein and creatinine are determined by appropriate methods (see under Assessment of Renal Injury by Serum Chemistry and Assessment of Renal Injury by Urinalysis ) and a urine proteimcreatinine ratio is calculated. 

Whole blood and urine pH and Pco2 are measured quantitatively by an electrode blood-gas system and HCO3 concentrations are calculated. Plasma and urine Na+ and K+ concentrations are measured by flame photometry and CP concentrations by electrotitration. Plasma total protein concentrations and urine specific gravity are measured by refractometry, and hematocrits are determined by a microcapillary reader. Urine osmolalities are determined by freezing-point osmometry. Plasma creatinine concentrations are determined by the Jaffe method without deproteiniza-tion. 

The protein excretion rate is ordinarily determined from a 24-hour urine collection because random specimens vary considerably in protein concentration. However, a more convenient alternative is to determine, in random samples, the ratio of protein to creatinine (protein-creatinine index). Creatinine concentration is relatively constant in any one subject, and the index correlates well with the 24-hour total excretion of protein. Total protein determination, however, does not discriminate between individual proteins, and when 24-hour excretion or protein-creatinine index values are near normal, estimation of one or two individual representative proteins is preferred. When protein excretion... 

Dye-Binding Methods. Dye-binding methods are based on the ability of proteins to bind dyes, such as Coumassie brilliant blue (CBB). The unequal affinities and binding capacities of individual proteins for dyes are a limitation and are complicated further by the inability to define a consistent material for use as a calibrator. The dye-binding method of greatest contemporary interest uses CBB G-250 for assay of total protein in CSF or urine. CBB binds to protonated amine groups of amino acid residues in the polypeptide chain, resulting in decreased absorbance at 465 nm and increased absorbance at 595 nm. 

The reference interval for urinary total protein is 1 to 14mg/dL. The excretion rate at rest is 50 to 80mg/d, but many laboratories indicate the reference value as less than lOOmg/d (less than 150mg/d in pregnancy). The concentration may reach 300mg/d in urine of healthy subjects after exercise. 

Measurement of Total Protein There are numerous methods used for the measurement of protein in urine (see Chapter 20). They include (1) the original Lowry method,(2) turbidimetry after mixing with trichloroacetic or sulfosalicylic acid, (3) turbidimetry with benzethonium chloride (benzyl dimethyl (2-[2-(p-1,1,3,3-tetramethyl butylphenoxy)ethoxy]ethyl ammonium chloride,(4) dye binding with Coomassie Brilliant Blue, and (5) dye binding with pyrogallol red molybdate. ... 

The normal urinary total protein excretion is less than 150mg/24hr. The proteins excreted are made up of mostly albumin (50% to 60%) and some smaller proteins, together with proteins secreted by the tubules, of which Tamm-Horsfall glycoprotein (THG) is one. The normal concentrations of proteins found in urine are listed in Table 24-1. 

Figure 24-5 Frequency distribution of quantitative results combined with returns of "nil, zero, or not detected for distributions of salt solution and normal urine. Quality control of total protein measurement demonstrates the widespread variation in results achieved using different methods, (from Chombers RE, Bullock DG, Wh/cfier JT. Urinary total protein estimation Fact or fiction Nephron 1989 53 33. Reproduced with permission of S. Karger AG, Basel, Switzerland.)...

In general, proteinuria reflects albuminuria. Albumin is readily measured by quantitative immunoassay methods capable of detecting urine albumin at low concentrations, and several groups have demonstrated that urinary total protein measurement can be replaced by that of urine albumin.This may provide a more specific and sensitive measure of changes in glomerular permeability and is... 

BaUantyne EC, Gibbon J, O Reilly D. Urine albumin should replace total protein for the assessment of glomerular proteinuria. Ann Clin Biochem 1993 30 101-3. 

Newman DJ, Thakkar H, Medcalf EA, Gray MR, Price CP. Use of urine albumin measurement as a replacement for total protein. Clin Nephrol 1995 43 104-9. 

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