Urinary ammonium measurement by the auto-analyzer method

Katagawa, Kazuyuki; Nagashima, Tatsuo; Inase, Naohiko; Kanayama, Masaaki; Chida, Mamoru; Sasaki, Sei; Marumo, Fumiaki

doi:10.1038/ki.1989.193

Cited by 14 publications

(18 citation statements)

References 9 publications

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“…Thus, estimation of ammonium excretion is usually necessary for the assessment of the renal response to metabolic aci dosis. Unfortunately, a direct assay for ammonium in the urine is not generally available on a routine basis through the hospital biochemistry laboratory [26]. Thus, there is a need for an indirect assessment of the rate of ammonium excretion using tools that are generally avail able to the clinician.…”

Section: Urine Electrolytes In the Differential Diagnosis Of Metabolimentioning

confidence: 99%

Urine Electrolytes and Osmolality: When and How to Use Them

Kamel

Éthier²,

Richardson³

et al. 1990

Am J Nephrol

124

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The purpose of this review is to provide an update on the use of the urine electrolyte and osmolality measurements in patients with disorders of fluid, electrolytes, and/or acid-base metabolism. It is critical to appreciate that there are no ‘normal values’ for these parameters, only ‘expected values’ relative to clinical situations. Pitfalls in the interpretation of each electrolyte in the urine are also provided. To detect a mild to moderate degree of reduction of the ‘effective’ intravascular volume, both urine sodium (Na) and chloride (CI) concentrations should be measured. Pitfalls in this assessment are abnormal renal and adrenal function and the use of diuretics. Insights into the etiology of the low ‘effective’ intravascular volume can be deduced by comparing the urine Na, potassium (K), and CI concentrations. The urine net charge (CI vs. Na + K) is the most reliable way to estimate the urine ammonium concentration short of its direct measurement, an assay that is not provided by most laboratories. This measurement is important in the differential diagnosis of hyperchloremic metabolic acidosis. To examine the renal response to hypokalemia or hyperkalemia, the two components of K excretion (K secretion and urine flow rate) should be examined separately. The former is evaluated using the transtubular K, concentration gradient. The urine osmolality is used to assess antidiuretic hormone action and the osmolality of the renal medulla and to determine the etiology of polyuria and/or hypernatremia. The urine osmolality can also be used to assess the ammonium concentration, using the urine osmolal gap, and to detect unusual urine osmoles.

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Section: Urine Electrolytes In the Differential Diagnosis Of Metabolimentioning

confidence: 99%

Urine Electrolytes and Osmolality: When and How to Use Them

Kamel

Éthier²,

Richardson³

et al. 1990

Am J Nephrol

124

View full text Add to dashboard Cite

show abstract

“…Direct Measurement of Urinary NH 4 + . To date, NH 4 + has not routinely been measured directly because the traditional methods utilized for this purpose, such as the formaldehyde titration method, are labor intensive and expensive (45). However, the enzymatic assay used in many clinical laboratories for measuring serum NH 4 + can be easily modified by predilution of the urine by 1:100 or greater, thereby enabling this determination to be accomplished using an autoanalyzer (45,46).…”

Section: Indirect Estimates Of Urinary Nhmentioning

confidence: 99%

“…To date, NH 4 + has not routinely been measured directly because the traditional methods utilized for this purpose, such as the formaldehyde titration method, are labor intensive and expensive (45). However, the enzymatic assay used in many clinical laboratories for measuring serum NH 4 + can be easily modified by predilution of the urine by 1:100 or greater, thereby enabling this determination to be accomplished using an autoanalyzer (45,46). Studies comparing the accuracy of this method with the formaldehyde titration method show good agreement (45,46), and reveal that the determination can be completed within 30 minutes.…”

Section: Indirect Estimates Of Urinary Nhmentioning

confidence: 99%

“…However, the enzymatic assay used in many clinical laboratories for measuring serum NH 4 + can be easily modified by predilution of the urine by 1:100 or greater, thereby enabling this determination to be accomplished using an autoanalyzer (45,46). Studies comparing the accuracy of this method with the formaldehyde titration method show good agreement (45,46), and reveal that the determination can be completed within 30 minutes. The estimated cost of each determination is approximately $5-6 USD (46).…”

Section: Indirect Estimates Of Urinary Nhmentioning

confidence: 99%

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Differential Diagnosis of Nongap Metabolic Acidosis

Kraut

Madias

2012

Clinical Journal of the American Society of Nephrology

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SummaryNongap metabolic acidosis is a common form of both acute and chronic metabolic acidosis. Because derangements in renal acid-base regulation are a common cause of nongap metabolic acidosis, studies to evaluate renal acidification often serve as the mainstay of differential diagnosis. However, in many cases, information obtained from the history and physical examination, evaluation of the electrolyte pattern (to determine if a nongap acidosis alone or a combined nongap and high anion gap metabolic acidosis is present), and examination of the serum potassium concentration (to characterize the disorder as hyperkalemic or hypokalemic in nature) is sufficient to make a presumptive diagnosis without more sophisticated studies. If this information proves insufficient, indirect estimates or direct measurement of urinary NH 4 + concentration, measurement of urine pH, and assessment of urinary HCO 3 2 excretion can help in establishing the diagnosis. This review summarizes current information concerning the pathophysiology of this electrolyte pattern and the value and limitations of all of the diagnostic studies available. It also provides a systematic and cost-effective approach to the differential diagnosis of nongap metabolic acidosis.

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“…6 Interestingly, Katagawa and colleagues compared the accuracy of this method to the formaldehyde titration method and found good agreement. 7 In our hospital, we directly measure urine ammonium levels by enzymatic assay using glutamate dehydrogenase with predilution of the urine by 1:200 in a regular serum ammonium analyzer. The advantages are simple, fast, accurate, and economical results.…”

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confidence: 99%