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Questions and Answers
Which substance is predominantly excreted by a healthy individual among the Coproporphyrin forms?
Which substance is predominantly excreted by a healthy individual among the Coproporphyrin forms?
What is the source of purine bases like adenine, guanine, and xanthine in the body?
What is the source of purine bases like adenine, guanine, and xanthine in the body?
In what condition would lactic acid be found in the urine?
In what condition would lactic acid be found in the urine?
Which amino acid is responsible for the formation of p-(OH)-phenylacetic acid and p-(OH)-phenylpropionic acid?
Which amino acid is responsible for the formation of p-(OH)-phenylacetic acid and p-(OH)-phenylpropionic acid?
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Which substance is known to be a product of tryptophan metabolism?
Which substance is known to be a product of tryptophan metabolism?
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What is the primary end product of the enzyme hyaluronidase's action on polysaccharides?
What is the primary end product of the enzyme hyaluronidase's action on polysaccharides?
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Which pigment is considered the most important among urochrome pigments?
Which pigment is considered the most important among urochrome pigments?
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'Chyluria' refers to the presence of what substance in the urine?
'Chyluria' refers to the presence of what substance in the urine?
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In which condition does urine exposure to air lead to a dark brown or black appearance due to oxidation?
In which condition does urine exposure to air lead to a dark brown or black appearance due to oxidation?
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What substance results from the union of benzoic acid with glycine?
What substance results from the union of benzoic acid with glycine?
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Study Notes
Ketone Bodies
- Ketone bodies are intermediate products in the breakdown of fatty acid chains
- Three main types: acetone, acetoacetic acid, and β-(OH)-butyric acid
- Acetone is a decomposition product of acetoacetic acid
- Normally, 3-20 mg/d of ketone bodies are excreted
- Increased excretion in:
- Starvation
- Impaired carbohydrate metabolism (DM)
- Pregnancy
- Ether anesthesia
- Alkalosis
- Excess fat metabolism (in many animals)
Urine Composition
- Anuria: complete stoppage of urine
- Oliguria: reduced amount of urine
- Polyuria: increased amount of urine
- Nocturia: increased amount of urine at night
- Normal constituents of urine:
- Urea (principle end product of protein metabolism in mammals)
- Ammonia (present in inorganic combination or in the free state)
- Uric acid (end product of purine oxidation in the body)
- Creatinine
- Urine A.Volume (750-2500 ml/d in normal adults)
Renal Function and Clearance
- Renal clearance is a quantitative measure of renal function
- Inulin is used to measure renal clearance (120 mL/min in healthy individuals)
- Energy requirements for concentrating urine and transporting it through membranes are high
- ATP is obtained from oxidative metabolism of fatty acids, ketone bodies, and amino acids in the proximal tubule
Urine Constituents
- Urea:
- Comprises 80-90% of total urinary nitrogen
- Excretion is directly related to protein intake
- Increased excretion in:
- Protein catabolism
- Fever
- Diabetes
- Excess adrenocortical activity
- Decreased excretion in:
- Last stages of fatal liver disease
- Acidosis
- Ammonia:
- Normally present in small amounts
- Increased excretion in acidosis
- Decreased excretion in ketosis
- Uric acid:
- Derived from dietary nucleoprotein and breakdown of cellular nucleoprotein
- Normal output: 0.5-1.0 g/24 h
- Increased output in:
- Leukemia
- Severe liver disease
- Gout
- Analysis can be done using Folin test or uricase enzyme
- Citric acid:
- Normal urine constituent
- Excretion: 300-1500 mg/24 h
- Enhanced in alkaline urine and by estrogens
- Reduced in acid urine and by androgens
- Amino acids:
- Normally excreted in small amounts
- Increased excretion in:
- Terminal liver disease
- Certain types of poisoning
- Cystinuria
- Porphyrins:
- Coproporphyrin is the excreted form in normal adults
- Normal output: 60-280 μg/d
- Increased output in certain liver diseases
- Other substances:
- Purine base
- Aromatic acid and oxyacids
- Homogentisic acid (found in alcaptonuria)
- Kinurenic acid (product of tryptophan metabolism)
- Oxaluric acid (found in traces in normal urine)
- Hippuric acid (formed by union of benzoic acid with glycine)
- Lactic acid (found in urine when O2 supply is diminished)
- Glucuronic acid (end product of polysaccharide-splitting action of hyaluronidase)
- Fat and fatty acids (found in chyluria)
- Formic acid (excretion increased in methyl alcohol poisoning)
- Pigments (urochrome, uroerythrin, uroporphyrin, and melanin)
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Description
Test your knowledge on renal clearance, inulin clearance, urine concentration, energy demand in kidneys, and related concepts in kidney function.
