Urine pH - Urinalysis and General

Urine pH – Urinalysis and General

DISEASE	SUMMARY	JOURNAL PUBLISHED / LINK
Urinalysis to detect a wide range of disorders	(1)   Urinary pH can range from 4.5 to 8 but normally is slightly acidic (i.e., 5.5 to 6.5) because of metabolic activity. Ingestion of proteins and acidic fruits (e.g., cranberries) can cause acidic urine, and diets high in citrate can cause alkaline urine.15–17 Urinary pH generally reflects the serum pH, except in patients with renal tubular acidosis (RTA) (2)   In type I (distal) RTA, the serum is acidic but the urine is alkaline, secondary to an inability to secrete protons into the urine. Type II (proximal) RTA is characterized by an inability to reabsorb bicarbonate. This situation initially results in alkaline urine, but as the filtered load of bicarbonate decreases, the urine becomes more acidic. (3)   Determination of urinary pH is useful in the diagnosis and management of UTIs and calculi. Alkaline urine in a patient with a UTI suggests the presence of a urea-splitting organism, which may be associated with magnesium-ammonium phosphate crystals and can form staghorn calculi. Uric acid calculi are associated with acidic urine. (4)   Urine must be refrigerated if it cannot be examined promptly; delays of more than two hours between collection and examination often cause unreliable results.2 (5)   cleansing of the external genitalia often is recommended in women, with no proven benefit. (6)   Microhematuria is blood in urine that can only be seen under a microscope (7)   cloudy urine often is a result of precipitated phosphate crystals in alkaline urine, but pyuria also can be the cause.	American Family Physician, March 15, 2005◆ Volume 71, Number 6, 1153-1162 Jeff A Simerville 1, William C Maxted, John J Pahira Urinalysis: A Comprehensive Review
Urinalysis	(1)   Urine becomes increasingly acidic as the amount of sodium and excess acid retained by the body increases. Alkaline urine, usually containing bicarbonate-carbonic acid buffer, is normally excreted when there is an excess of base or alkali in the body. (2)   Urine pH is an important screening test for the diagnosis of renal disease, respiratory disease, and certain metabolic disorders. (3)   An accurate measurement of urinary pH can be done only on a freshly voided specimen. If urine must be kept for any length of time before analysis, it should be refrigerated. (4)   During sleep, decreased pulmonary ventilation causes respiratory acidosis. As a result, a first waking urine specimen is usually highly acidic. (5)   A diet rich in citrus fruits, most vegetables, and legumes will keep the urine alkaline. (6)   A diet high in meat and cranberry juice will keep the urine acidic.	Chemical Urinanalysis
GENERAL	Findings may help explain why females are more subjectthan males to calcium stones with a high phosphate content. Ahigher urine pH will increase urinary supersaturation withrespect to calcium phosphate, predicting formation of calciumphosphate in preference to calcium oxalate stones (24). We andothers have identified urine pH as the primary driver forcalcium phosphate supersaturation and calcium phosphate content of stones.	Am J Physiol Renal Physiol 314: F623–F629, 2018. Elaine M. Worcester,1Kristin J. Bergsland,1Daniel L. Gillen,2and Fredric L. Coe1 Mechanism for higher urine pH in normal women compared with men
Dietary acid-base issues	(1)     dietary acid–base load was significantly related to urine pH with more alkaline urine associated with a more alkaline dietary load. (2)     The non-dietary factors affecting urine pH are diabetic ketoacidosis, renal failure, diuretic medication and hypertension, but we found a relationship between diet and urine pH despite these factors. (3)     The urine pH of meat-eaters was significantly lower than non-meat-eaters (4)     Nonsignificant differences between the urine pH of omnivores and vegetarians (6·26 v. 6·45, respectively) (5)     A measurable difference in urine pH with dietary acid–base load and with fruit and vegetables and meat intakes in this population. The more alkaline the diet (lower PRAL) the more alkaline was urine pH, even after adjustment for age, BMI, physical activity and smoking habit and also after excluding for urinary protein, glucose, ketones, diagnosed high blood pressure and diuretic medication. (6)     Approximately 25 000 men and women aged 40–79 years: examination in 1993–7 in Norfolk (UK), as part of the European Prospective Investigation into Cancer and Nutrition (EPIC), a ten-country collaboration of diet and cancer and, in the EPIC-Norfolk study, other health outcomes(24).	British Journal of Nutrition (2008), 99, 1335–1343 Ailsa A. Welch1*, Angela Mulligan1, Sheila A. Bingham2 and Kay-tee Khaw3 Urine pH is an indicator of dietary acid–base load, fruit and vegetables and meat intakes: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk population study