Download BCH_PRACTICAL_ASSIGNMENT__ADISA_1

NAME; ADISA SAMUEL OLAWALE
MATRIC NUMBER: 13/MHS01/119
DEPARTMENT: MEDICINE AND SURGERY
COURSE: MEDICAL BIOCHEMISTRY PRACTICAL
DATE: 10-06-2015
QUESTION: DISCUSS GLUCOSURIA AND KETONURIA AS CLINICAL
SIGNIFICANCE OF GLUCOSE AND KETONE BODY METABOLISM
RESPECTIVELY
GLUCOSURIA
INTRODUCTION
Glucosuria can simply be defined as the excretion of glucose into the urine. Normaly, urine
contains no glucose because the kidneys are able to reclaim all of the filtered glucose back
into the bloodstream. Glucosuria is nearly always caused by elevated blood glucose levels,
most commonly due to untreated diabetes mellitus. Rarely, glucosuria is due to an intrinsic
problem with glucose reabsorption within the kidneys themselves, a condition termed renal
glucosuria. Glucosuria leads to excessive water loss into the urine with resultant dehydration,
a process called osmotic diuresis. It is an umbrella term used for “Sugar in Urine” so since
glucose is the most common sugar, it is not wrong to use them interchangeably.
MECHANISM OF GLUCOSURIA
Blood is filtered by millions of nephrons, the functional units that comprise the kidneys. In
each nephron, blood flows from the arteriole into the glomerulus, a tuft of leaky capillaries.
The Bowman's capsule surrounds each glomerulus, and collects the filtrate that the
glomerulus forms. The filtrate contains waste products (e.g. urea), electrolytes (e.g. sodium,
potassium, and chloride), amino acids, and glucose. The filtrate passes into the renal tubules
of the kidney. In the first part of the renal tubule, the proximal tubule, glucose is reabsorbed
from the filtrate, across the tubular epithelium and into the bloodstream. The proximal tubule
can only reabsorb a limited amount of glucose. When the blood glucose level exceeds about
160 – 180 mg/dl, the proximal tubule becomes overwhelmed and begins to excrete glucose in
the urine. This point is called the renal threshold of glucose (RTG). Some people, especially
children and pregnant women, may have a low RTG (less than ~7 mmol/L glucose in blood
to have glucosuria). If the RTG is so low that even normal blood glucose levels produce the
condition, it is referred to as Renal Glycosuria. Glucose in urine can be identified by
Benedict's qualitative test.
1
KETONURIA
INTRODUCTION
Ketonuria is a medical condition in which ketone bodies are present in the urine. It is seen in
conditions in which the body produces excess ketones as an indication that it is using an
alternative source of energy. It is seen during starvation or more commonly in type I diabetes
mellitus. Production of ketone bodies is a normal response to a shortage of glucose, meant to
provide an alternate source of fuel from fatty acids. Ketone bodies include; Acetoacetic acid,
beta hydroxybutyric acid and Acetone.
MECHANISM OF KETONURIA
Ketones are metabolic end-products of fatty acid metabolism. In healthy individuals, ketones
are formed in the liver and are completely metabolized so that only negligible amounts
appear in the urine. However, when carbohydrates are unavailable or unable to be used as an
energy source, fat becomes the predominant body fuel instead of carbohydrates and excessive
amounts of ketones are formed as a metabolic by-product. Higher levels of ketones in the
urine indicate that the body is using fat as the major source of energy. Acetone is also
produced and is expired by the lungs. Normally, the urine should not contain a noticeable
concentration of ketones to give a positive reading. As with tests for glucose, acetone can be
tested by a dipstick or by a lab. The results are reported as small, moderate, or large amounts
of acetone. A small amount of acetone is a value under 20 mg/dl; a moderate amount is a
value of 30–40 mg/dl, and a finding of 80 mg/dl or greater is reported as a large amount.
Causes
 Metabolic abnormalities such as diabetes, renal glycosuria, or glycogen storage
disease
 Dietary conditions such as starvation, fasting, high protein, or low carbohydrate diets,
prolonged vomiting, and anorexia
 Conditions in which metabolism is increased, such as hyperthyroidism, fever,
pregnancy or lactation
2