The diagnosis of urinary tract infection depends on the characteristics clinical features and demonstration of more than 100,000/ml organisms in a mid-stream specimen of urine, or any organism in urine from a supra pubic aspiration in urinalysis.
Ideally, results of urine culture and sensitivities should be available before treatment, but if the patient is in discomfort treatment may be started while awaiting the result.
Potassium citrate mixture 10 ml three times daily in half glass of water alkalinizes the urine and relieves dysuria. Alternatively, a heating pad or a hot-water bottle may ease the pain.
Since infection is usually due to E. coli, initial use of antibiotics like trimethoprim/sulfamethoxazole 250 mg b.d (twice daily) or amoxicillin 250 mg t.d.s (three times a day) is rational. The antibiotic can be changed if a resistant organism is identified or the response is unsatisfactory. Alternatively, a class of drugs known as quinolones can be used to treat UTI. These include Ciprofloxacin 250-500mg 12 hourly for 1-3 days or Norfloxacin 400 mg 12 hourly for 1-3 days.
Symptomatic relief usually occurs within 48 hours. A 3-day course is adequate and is superior to single dose treatment.
If infection fails to settle on appropriate antibiotics or recurs rapidly after stopping antibiotics, further investigations must be done. Failure to respond to treatment suggests inappropriate antibiotics, failure to complete the full course of antibiotics, resistant organisms, underlying obstruction, calculus (stone), tumor, urinary retention or specific infection like TB.
Re infection with other organisms, or with the same organism after an interval, is not uncommon, particularly in sexually active women.
Women with recurrent urinary infections must adopt some simple measures. These measures are mentioned below:·

• Fluid intake of at least two liters/day·
• Regular emptying of bladder (3 –hour intervals by day and before retiring) ·
• Ensure complete emptying of bladder·
• Double micturition (urination) if reflux is present. (The patient should be advised, particularly before retiring for the night, to empty the bladder and then attempt to empty the bladder a second time approximately 10-15 minutes later) ·
• Emptying bladder before and after sexual intercourse·
• Application of 0.5% cetrimide cream to periurethral area before intercourse

But it is recommended that sexual intercourse should be avoided when infected.
During treatment, one must not take anything that irritates bladder like coffee, alcohol and spicy foods. One must also try his/her best to quit smoking, as it is a well-documented fact that smoking is one of the major causes of bladder carcinoma (cancer).
Finally, it is said that regular drinking of cranberry juice may be helpful in preventing the recurrence of UTI in women. In fact, it is the conclusion of a study published in the British Medical Journal (June 29, 2001). Although cranberry juice does not directly kill the bacteria but it is said that it prevents the adhesion of bacteria to the bladder walls.
Since cranberry juice is readily available product, it might be helpful in reducing the need for antibiotics.

Urinary tract infection is associated with multiplication of organisms in the urinary tract and is defined by the presence of more than a hundred thousand organisms per ml in mid stream sample of urine (MSU). UTI is common in women; in fact the majority of women will have a UTI some time during their life. UTI is usually uncommon in men except in elders.
Before we discuss the symptoms of urinary tract infections, it must be kept in mind that UTI can be further categorized into two categories, the upper urinary tract infection and the lower urinary tract infection. Symptoms vary according to these categories.
The lower urinary tract infection includes urethritis (inflammation and infection of urethra), cystitis (inflammation and infection of bladder) and prostatitis (inflammation and infection of prostate).
There is often an abrupt onset of frequency of micturition (urination) and dysuria (painful urination with burning sensation). Scalding pain is felt in the urethra during micturition. Cystitis may give rise to supra pubic pain in women and in case of men, sense of pressure or pain in rectum, during and after voiding.
After the bladder has been emptied, there may be an intense desire to pass more urine due to spasm of the inflamed bladder wall. Supra pubic tenderness is often present or may occur on examination PR (per rectum) or PV (per vagina).
Urine may have an unpleasant odor and appear cloudy (indicating pus in the urine).
Gross hematuria (blood in the urine) may occur.
The presence of pus cells in the urine (pyuria) is common, but not invariable.
Generalized symptoms like tiredness and weakness may accompany UTI, but fever is uncommon in lower urinary tract infection, but may be present if infection reaches to blood or kidneys.
Infants usually do not have characteristic symptoms as that of adults or elder children. They may have only fever and no other symptoms. But it must be kept in mind that UTI affects both male and female infants. Infants suffering from UTI are mostly irritable, with feeding problems accompanied by diarrhea and vomiting. Since nature of symptoms is so non-specific, UTI is difficult to diagnose in infants.
Elderly people usually present with fever, altered mental status, low body temperature (hypothermia) along with poor appetite.
In case of upper urinary tract infection when kidney gets infected, the condition is known as pyelonephritis. This condition presents with moderately high fever, loin pain (usually about at waist level), dysuria, cloudy or bloodstained urine and rigors.
Another fact must not be ignored that sometimes the symptoms of UTI may resemble with those of sexually transmitted diseases (STDs).

Before we discuss the causes of urinary tract infection (UTI), we cannot ignore the significance of definition of UTI. Urinary tract infection (UTI) implies multiplication of organisms in the urinary tract, and is defined by the presence of more than 100,000 organisms per ml in a midstream sample of urine (MSU).
A very important fact must not be ignored at any cost that such infections are much more common in women, about one-third of whom have a UTI at some time. The prevalence of UTI in women is about 30% at the age of 20, increasing by about 1% in each subsequent decade. In males UTI is uncommon except in the first year of life and in men over 60, in whom a degree of urinary tract obstruction due to prostatic hypertrophy is common. UTI causes considerable morbidity, and in small minority of cases, renal damage and chronic renal failure.
Risk factors include pregnancy, urinary tract malformations, urinary tract obstruction, calculus or renal stones, prostatic obstruction, bladder diverticulum, spinal injury, trauma, urinary tract tumor, diabetes mellitus and immunosuppression as in case of AIDS.
Now we move on to the causes of urinary tract infection. UTI may be uncomplicated or complicated; the latter may result in permanent renal damage, the former rarely (if ever) do so. Uncomplicated infections are almost invariably due to single strain of organisms.
Outside hospitals, E. coli derived from fecal reservoir accounts for about 75% of infections, the remainder being due to Proteus, Pseudomonas species, streptococci or Staphylococcus epidermidis. In hospitals a greater proportion of infections are due to organisms such as Klebsiella or streptococci, but fecal E. coli still predominates. Certain strains of E. coli have a particular propensity to invade the urinary tract. They possess surface fimbriae, at the tips of which are lectin molecules, which bind to glycolipid or glycoprotein surface receptors on the urothelium.
The first stage in the development of UTI is colonization of the periurethral zone with pathogenic fecal organisms. The urothelium of susceptible persons may have more receptors to which virulent strains of E. coli become adherent. Colonization by the pathogenic bacteria may be facilitated by lack of personal hygiene, wearing of sanitary towels and local infections like vaginitis.
In women, the ascent of organisms into the bladder is facilitated by the short urethra and absence of bactericidal prostatic secretions, while the longer male urethra protects against transfer of bacteria to the bladder. It must be kept in mind that multiplication of bacteria occurs in bladder, from where they reach the ureters and kidneys easily, facilitated by vasicoureteric reflux and dilatation of hypo tonic ureters.
Sexual intercourse naturally causes minor urethral trauma and may transfer bacteria from the perineum into the bladder.
Instrumentation of the bladder may also introduce organisms.
Residual urine left after voiding interferes with mucosal defense mechanisms; thus patients with bladder outflow obstruction, gynecological abnormalities, pelvic floor weakness or neurological problems are susceptible to infection.
Injury to the mucosa and the presence of a foreign body in the bladder also depress vesical defense mechanisms.

A question arises in mind with an exclamation mark, can a simple test like Urinalysis or UA is really capable of telling us about renal diseases or what is wrong happening in our body!
The answer is yes. It is a simple yet quite informative test especially in assessing renal functions and additionally it may give us some more information.
But what is Urinalysis? UA is actually in very simple terms the Analysis Of Urine.
Now we would be discussing UA step by step so that we may know how does this test helps us in gaining some important information about our renal functions:
1-Color of Urine
Normal: Ranges from colorless to deep yellow depending on the concentration of the urochrome pigment.
Red: Indicates hemoglobinuria, myoglobinuria or hematuria (blood in urine)
Orange: This color happens if a person is taking rifampicin (This drug is taken by patients who are suffering from Tuberculosis or TB)
Yellow: Indicates concentrated urine which usually occurs in dehydration, jaundice, and with the use of sulfasalazine and Vitamin B Complex)
Green: Methylene Blue (This is a blue dye and is found as a component in several medicines)
Black: Happens in severe hemoglobinuria and in case of use of methyldopa.
Brown: Indicates bilirubin and also happens with use of phenothiazines.
2-Volume of Urine
Normal volume of urine is 800-2500 ml/day. In case of Oliguria, urine volume is less than 300 ml/day. And in Anuria, urine volume is less than 100 ml/day. It is very important to note that complete anuria suggests either an acute vascular event or total urinary obstruction; even in the most severe intrinsic renal disorders some urine is usually still produced. Polyuria, which refers to the production of an excess volume of urine, may have a number of causes like:
-Excess fluid intake
-Osmotic, e.g. hyperglycemia
-Cranial diabetes insipidus (loss of antidiuretic hormone-ADH)
-Nephrogenic diabetes insipidus (NDI) (tubular dysfunction)

• Genetic tubular cell defects: ADH receptor, aquarian mutations
• Drugs/Toxins: lithium, diuretics, hypercalcemia, Interstitial renal disease

3-Specific Gravity of Urine

It varies with the quantity of urine. Its normal range is 1.002 to 1.025. Estimation is required in investigation of polyuria or SIADH (Syndrome of Inappropriate Antidiuretic Hormone Hypersecretion). Persistently low specific gravity suggests chronic renal failure or diabetes insipidus while high specific gravity suggests dehydration or diabetes mellitus with presence of large amount of glucose in the urine.
4-Reaction of Urine
Fresh urine is acidic with an average pH of 6.The pH is important in investigation and management of renal tubular acidosis. Distal tubular acidosis should be suspected if the early morning urine is consistently alkaline and cannot be acidified.Infection with urea-splitting microorganism Proteus mirabilis can cause urine alkaline that favors renal calcium stone formation.
5-Glucose
Glucose in urine usually indicates diabetes but it may occur in impaired renal tubular ability to absorb glucose (renal glycosuria) such as in Fanconi’s syndrome. False positive or negative results may occur if patient is taking large doses of Vitamin C or taking tetracyclines or levodopa.
6-Ketones
Ketone in the urine of diabetic patient is an important indication of diabetic ketoacidosis. Ketones may be present in urine due to starvation also.
7-Protein
Normal protein loss from urine is less than 150 mg/24 hours. Causes of proteinuria are as following:
-Primary renal diseases

• Different types of glomerulonephritis

-Secondary renal diseases

• Systemic diseases: diabetes, hypertension and amyloidosis
• Drugs: captopril, penicillamine, heroine and NSAIDs (Non-Steroidal Anti-Inflammatory Drugs)
• Infections: Hepatitis B, Infective Endocarditis, Malaria and AIDS
• Allergy: Vaccine and bee sting

8-Microscopy

-White Blood Cells (WBCs)

More than 10 or more WBCs (White Blood Cells) per cm indicate Urinary Tract Infection or UTI (mostly) but it may also present in patients with stones, tubulointerstitial nephritis, tuberculosis and papillary necrosis.

-Red Blood Cells (RBCs)

Presence of 2-5 RBCs per high power field (of microscope) indicates positive test for hematuria and can be detected on dipstick. Red cells may come from glomeruli or below. RBCs of glomeruli origin tend to be dysmorphic and have many sizes and shapes whereas RBCs of non-glomeruli origin are uniform in size and shape.

-Casts

Theses are cylindrical structures that form within the kidney tubules by the coagulation of proteins. Their various types are discussed below:

A-Hyaline Cast: These are present in concentrated urine, in fever, after exercise and after diuretic therapy.

B-Granular Cast: Theses are found in chronic glomerulitis, diabetic nephropathy and malignant hypertension.

C-White Blood Cell Cast: These are found in acute pyelonephritis.

D-Red Blood Cell Cast: These are found in acute tubular necrosis and interstitial nephritis.

E-Broad Waxy Cast: These are found in chronic renal failure.

-Crystals

-Uric Acid Crystals: Found in acidic urine, hyperuricosuria and in acute uric acid nephropathy.

-Calcium Phosphate Crystals: Found in alkaline urine.

-Calcium Oxalate Crystals: Found in hyperoxaluria and in acidic urine.

-Cystine Crystals: Found in cystinuria.

So, in the end, we can conclude easily that Urinalysis, despite being a simple test provides us ample information not only about the renal diseases but may also pinpoint some other diseases like diabetes mellitus and malignant hypertension.

Before we discuss Kidney Function Tests, in medical terms Renal Function Tests (and it is always a good practice to use appropriate term instead of layman’s term), it is important to know why do we perform these tests. As we know kidney is one of a vital organ of human
body and performs at least 4 functions:

1- Excretory Functions: Helps in excretion of waste products and drugs.

2- Regulatory Functions: Controls body fluid volume and composition.

3- Endocrine Functions: Produces erythropoietin, rennin and prostaglandins.

4- Metabolic Functions: Metabolizes Vitamin D and small-molecular-weight proteins.

So, now we know the real importance of a healthy kidney. But what if
something wrong happens to this vital organ, then by which means we are
going to assess its functions?

The answer lies in the renal function
tests, which tell us about the overall status of kidney’s functions.

There are 3 major renal function tests, which we would be discussing
below one by one:

1-Glomerular Filtration Rate (GFR)

The GFR provides a useful index of overall renal function. It measures the amount of plasma ultra filtered across the glomerular capillaries and correlates well with the ability of the kidneys to filter fluids and various substances. Daily GFR is in the range of 100-120 ml/min.A low GFR is an evidence of serious progressive renal disease and indicates a decrease in total functioning renal mass. The GFR reduces in both acute and chronic renal failure.GFR can be estimated by the creatinine clearance with the help of following formula:

C=U multiplied with V/P where:

C: Creatinine Clearance

U: Urinary Clearance mg/dl

P: Plasma Creatinine mg/dl

V: Urine Flow Rate ml/min

Decreased GFR manifests as raised serum urea and creatinine. However serum urea and creatinine are not elevated above the normal range until there is a reduction of 50-60% in the GFR. Therefore, it should be noted that normal urea and creatinine levels do not rule out renal
insufficiency and when serum urea and creatinine begin to rise, more than 50-60% of renal damage has occurred.More accurate measurement of GFR is now most easily undertaken by ascertaining the clearance of 51Cr-labelled ethylenediamine-tetracaetic acid (EDTA).

2-Serum Urea

Urea is produced in the liver and is the end product of protein catabolism. Urea is freely filtered by the glomerulus and about 30-70% is reabsorbed in the nephrons. It is very important to note that dehydration causes increased urea reabsorption. Therefore urea level increases during dehydration as in case of acute diarrhea while the renal function is preserved and creatinine is normal. A normal urea to creatinine ratio is 20:1.This ratio is increased in dehydration while
the ratio remains same in renal insufficiency. There are also some other factors that affect serum urea level such as following:

Increased serum urea independent of GFR

• Dehydration
• Catabolic state
• High protein diet
• Glucocorticoids
• Tetracyclines

Decreased serum urea independent of GFR

• Liver disease
• Malnutrition
• Low protein diet
• Old age

3-Serum Creatinine

Creatinine is by far the most useful clinical test in assessing progression of renal failure. However, at least 50% of renal function is lost before rising serum creatinine. Therefore, normal level of creatinine does not rule out impairment of renal function.

Serial estimation of serum creatininine provides the best indication of state of renal function in patient with Chronic Renal Failure (CRF).

Creatinine is actually the product of muscle metabolism .It is freely filtered and not reabsorbed, however small amount is eliminated by tubular secretion that increases with dehydration overestimating the GFR.

As in case of serum urea, there are factors that affect serum
creatinine which are mentioned below:

Increased serum creatinine independent of GFR

• Ketoacidosis
• Drugs like Cephalothin, Cefoxitin, Aspirin, Cimetidine, and
  Trimethoprim

Decreased serum creatinine independent of GFR

• Advanced age
• Liver disease
• Cachexia

Before we discuss types of kidney stones, this fact must be kept in mind that different types of stone occur in different parts of the world, for example, bladder stones occur mostly in countries with hot climates, and this fact also must not be ignored that dietary factor probably plays vital part in determining the varying patterns of renal stones.Now we will discuss different types of stones one by one along with their peculiar characteristics:
1. Calcium Oxalate Stone (75 %)
Among all renal stones, this one is the most common. It is also called as “Mulberry” calculi. It is hard, single and has irregular sharp projections or spikes just like sea urchin. And due to these sharp projections, it causes hematuria (blood in the urine) very early, resulting in deposition of blood over the stone giving a dark color to the stone. Usually, it occurs in infected urine and contains alternate layer of calcium and bacterial vegetation. It is easily visualized in
plain X-Ray KUB (Kidney, Ureter and Bladder).
2. Phosphate Stone (15%)
This stone is smooth and round in shape while dirty white to yellow in color. It consists of triple phosphate of calcium, magnesium and ammonium and commonly occurs in renal pelvis and tends to grow in alkaline urine.As it enlarges in the pelvis, it grows within the major and minor calyces and slowly forms Staghorn calculus. This calculus produces recurrent urinary tract infection and hematuria and slowly damages the renal parenchyma. This stone is common in women with recurrent urinary tract infection. It is also known as Struvite or Infection Stone.
3. Uric Acid Stone or Urate Calculi (5%)
These are multiple, small hexagonal, faceted and yellow to light brown colored stones containing calcium oxalate, which makes them opaque. It must be noted that pure uric acid stones are radiolucent. These stones occur in acidic urine and are common in those patients who
consume red meat.
4. Cystine Calculus (2%)
Cystinuria is an inborn error of metabolism, which occurs due to decreased resorption of cystine from renal tubules. Such stones occur in young girls at puberty. Whenever there is an increased excretion of cystine in urine, it will result in cystine calculus. These stones are hard. Their color is white, pink or yellow when first removed but on exposure, color changes to a greenish hue. Although, they are translucent but it must be kept in mind that these stones are radio-opaque due to sulphur content.
5. Xanthine and Pyruvate Stones
These stones are usually rare and they happen if there is an inborn error of metabolism. They are smooth and round, brick red in color and show a lamellar (flat and thin) structure.
6. Indigo Calculi
These calculi are blue in color and the name is derived from indican. These calculi occur very rarely.

It is a well-documented fact that even after surgical removal of kidney stones, up to 50% of patients may have recurrence within 5 years. Therefore, some preventive measures must be taken in order to avoid kidney stones in the future.
In the longer term, a daily urine output of at least 2 liters is advisable in all patients with stone disease. Fluid intake should therefore be about 3 liters per day---more if the climate or the patient’s occupation causes much sweating. Suitable measures should be implied to correct any known cause of stone formation. Preparations containing vitamin D must be avoided, even milk intake has to be reduced.
Idiopathic hypercalciuria can be helped by reduction of sodium intake (low salt intake) and by the use of a thiazide diuretic. Reduction of calcium intake is not recommended unless it is very high, as it may lead to a negative overall calcium balance and reduction of bone mass which ultimately makes bones weaker, also reduction of calcium intake causes increased oxalate absorption and excretion.
Citrate excretion can be increased by daily administration of potassium nitrate or potassium bicarbonate. Alternatively, lemon juice may be a very good dietary source. Hypokalemia should be prevented as it leads to a reduction in citrate excretion.
In patients with recurrent oxalate stones, foods and some liquids rich in this salt, such as rhubarb, spinach, tomatoes, strawberries, chocolate and tea, should be avoided. Persons who have passed several uric acid or urate stones benefit from allopurinol, 100-300 mg daily, depending on renal function. Allopurinol also has a place in treating calcium oxalate stone disease, since urates may contribute by acting as a nidus (nest) for stone formation.
Phosphate-containing calculi are formed only in alkaline urine; hence acidifying the urine by giving ammonium chloride may be effective. In contrast, cystine and urate stones may be prevented or sometimes dissolved, by giving sufficient sodium bicarbonate to make the urine persistently alkaline, and ensuring a high urine output of 2-4 liters/day. When these measures fail or are unacceptable to the patient, treatment with D-penicillamine, a chelating agent, in a dose of 1-1.5 gram daily may be tried, although it is frequently associated with significant side effects.
In case of struvite stones, which are actually magnesium-ammonium-phosphate stones and quite common in women with recurrent urinary tract infections, protease inhibitors are advised. Frequently, struvite stones are large staghorn calculi, and urine pH is high. These stones are formed due to infection with urease producing organisms such as Proteus mirabilis, Pseudomonas, Klebsiella, Staphylococcus and Mycoplasma but not E. coli. Therefore, struvite stones are also called as Infection stones.