Renal system

Ans. When urinary output is less than 300 mL in a day on a normal diet.

Ans. It is the complete absence of urine production for the last 24 hours or less than 30 mL/day.

Ans. Polyuria means excessive urinary output, i.e. urine volume >3 L/day.

Ans. Causes are:

• Excess fluid intake
• Osmotic, e.g. hyperglycemia (DM) and hypercalcemia
• Cranial diabetes insipidus—Idiopathic (50%), mass lesion, trauma, and infection.
• Nephrogenic diabetes insipidus
  • Drugs/toxins, e.g. lithium and diuretics
  • Interstitial renal disease
  • Hypokalemia, hypercalcemia.

Haematuria is the presence of blood in the urine and can vary from frank bleeding (macroscopic) to the microscopic detection of red cells.

* John Murtagh’s General Practice, 6th Edition Page: 865

Haematuria is red blood cells in the urine arising from the kidneys or urinary tract.

* Macleod’s Clinical Examination, 13th Edition Page: 200

The causes of hematuria are:
– Glomerulonephritis
– Tumor
– Infection
– Infarction
– Cysts in kidney
– Stones.

* Pre-exam preparation for medicine, HN Sarker

Figure: Structure is adapted from Davidson’s Principles and Practice of Medicine, 22nd edition Page 475

Causes of hematuria are:
– Glomerulonephritis
– Urinary tract infection
– Infective endocarditis
– Infarction
– Benign familial hematuria
– Blood dyscrasia.

* Pre-exam preparation for medicine, HN Sarker

Causes of painless hematuria are:
– Glomerulonephritis
– Renal tuberculosis
– Infective endocarditis
– Benign familial hematuria
– Blood dyscrasia.

* Pre-exam preparation for medicine, HN Sarker

Causes of red urine are:

• Hematuria
• Hemoglobinuria
• Myoglobinuria
• Food dyes – For example, anthocyanins (beetroot)
• Drugs – For example,
  • Phenolphthalein—Pink when alkaline
  • Senna/other anthraquinones—Orange
  • Rifampicin—Orange
  • Levodopa—Darkens on standing
• Porphyria—Darkens on standing
• Alkaptonuria
• Bilirubinuria – For example, obstructive jaundice—Dark.

* Pre-exam preparation for medicine, HN Sarker 

Points to consider during history taking –

• Have you had an injury such as a blow to the loin, pelvis or genital area?
• Have you noticed whether the redness is at the start or end of your stream or throughout the stream?¹
• Have you noticed any bleeding elsewhere, such as bruising of the skin or nose bleed?
• Have you experienced any pain in the loin or abdomen?²
• Have you noticed any burning or frequency of your urine?
• Have you had any problems with the flow of your urine?
• Have you been having large amounts of beetroot, red lollies or berries in your diet?
• Could your problem have been sexually acquired?
• Have you been overseas recently?
• What is your general health like?
• Have you been aware of any other symptoms?
• Do you engage in strenuous sports such as jogging?
• Have you had any kidney problems in the past?
• Relevant drug history, especially with anticoagulants and cyclophosphamide.
• History of skin infection and scabies (AGN)
• History of oral ulcer, skin rash and joint pain (SLE)

¹Haematuria occurring in the first part of the stream suggests a urethral or prostatic lesion, while terminal haematuria suggests bleeding from the bladder. Uniform haematuria has no localising features.

Painful haematuria is suggestive of infection, urethral caruncle, calculi or kidney infarction, while painless haematuria is commonly associated with infection, trauma, tumours or polycystic kidneys.

²Loin pain can occur as a manifestation of nephritis and may be a feature of bleeding in cancer of the kidney or polycystic kidney.

* John Murtagh’s General Practice, 6th Edition Page: 866

As follows:

1. Urinalysis by dipstick testing (e.g. Hemastixaffected derivatives—affected by vitamin C intake). 
2. Urine microscopy:
   • formed RBCs in true haematuria
   • red cell casts indicate glomerular bleeding
   • deformed (dysmorphic) red cells indicate glomerular bleeding
3. Urinary culture:
   • early culture is important because of the common association with infection and consideration of early treatment with antibiotics.
   • If tuberculosis is suspected, three early morning urines should be cultured for tubercle bacilli.
4. Urinary cytology:
   • this test, performed on a urine sample, may be useful to detect malignancies of the bladder and lower tract but is usually negative with kidney cancer.
5. Blood tests:
   • appropriate screening tests include a full blood count, ESR and basic kidney function tests (urea and creatinine).
   • If glomerulonephritis is suspected, antistreptolysin O titres and serum complement levels should be measured.
6. Radiological and other imaging techniques—available tests include:
   • intravenous urography (IVU); intravenous pyelogram (IVP)—the key investigation
   • ultrasound (less sensitive at detecting LUT abnormalities)
   • CT scanning
   • kidney angiography
   • retrograde pyelography
7. Direct imaging techniques:
   • these include urethroscopy, cystoscopy and ureteroscopy.
   • In all patients, regardless of the IVU findings, cystoscopy is advisable.
8. Kidney biopsy:
   • indicated if glomerular disease is suspected, especially in the presence of dysmorphic red cells on microscopic examination.

* John Murtagh’s General Practice, 6th Edition Page: 867-868

Proteinuria is excess protein in urine and indicates kidney disease.

* Macleod’s Clinical Examination, 13th Edition Page: 201

Proteinuria is the presence of abnormal quantities of protein in the urine, which may indicate damage to the kidneys.*

Note:

Whilst moderate amounts of low-molecular-weight protein pass through the healthy glomerular basement membrane (GBM), these proteins are normally reabsorbed by receptors on tubular cells. In healthy individuals, less than 150 mg of protein is excreted in the urine each day. The presence of larger amounts of protein is usually indicative of significant renal disease.**

* Google dictionary; ** Davidson’s Principles and Practice of Medicine, 22nd edition Page: 476

Proteinuria occurring after long-standing is called orthostatic proteinuria.

* * Pre-exam preparation for medicine, HN Sarker

Procedure:

1. Two-thirds of a test tube is filled with urine.
2. A blue litmus paper is emmersed to test the reaction of urine.
   • If alkaline, a few drops of 5% acetic acid is added to make urine acidic.
3. Then upper portion of urine is heated to boiling and checked.

* * Pre-exam preparation for medicine, HN Sarker

Normal reaction of urine is acidic.

* * Pre-exam preparation for medicine, HN Sarker

Interpritation:

• After heating if there is cloudiness, it indicates presence of protein or phosphate.
• A few drops of acetic acid is added and heated again, phosphate will dissolve but protein intensifies.

* * Pre-exam preparation for medicine, HN Sarker

* Davidson’s Principles and Practice of Medicine, 22nd edition Page: 476

As follows:

• Renal cell carcinoma
• Hydronephrosis or pyonephrosis
• Renal abscess
• Solitary kidney (due to hypertrophy) in lean and thin person.

*Long Cases in Clinical Medicine, ABM Abdullah

As follows:

• Polycystic kidney disease
• Bilateral hydronephrosis
• Amyloidosis
• Diabetic nephropathy in early stage
• Bilateral renal cell carcinoma (rare)
• Lymphoma (rare).

*Long Cases in Clinical Medicine, ABM Abdullah

The common renal diseases causing hypertension are:
– Glomerulonephritis
– Renovascular disease
– Interstitial diseases
– Renal artery stenosis
– Polycystic kidney disease.

*Pre-exam preparation for medicine, HN Sarker