Module 3: Toxicology - Section 14: Renal-urinary tract and the kidney
TOX 14.2: Occupational Renal-Urinary Tract Disease

INTRODUCTION:

The renal-urinary tract includes the kidney, ureters and bladder. Non-infective renal-urinary tract disease is not common in general practice and even less common in occupational medicine practice. Chronic renal disease and cancer tend to be specialist diagnoses and an occupational history if unlikely to be taken. Even if one is taken, a cause and effect link is difficult to establish because of the long latency of the disease and the non-specific nature of the association.

The most common causes of chronic non-infective renal disease in adult practice in South Africa are likely to be primary hypertension and diabetes. (Chronic infective causes such as schistosomiasis and even tuberculosis should be remembered). The most common "environmental" cause may be chronic or high dose analgesic use. The textbooks also refers to herbal medicine ingredients as another possible cause - this may have local relevance. Acute renal disease has many causes and the clinical context will usually direct investigations. Where a toxic cause is suspected, workplace exposures should always be investigated.

Where there is a known nephrotoxin in the workplace, you may want to do medical surveillance using clinical tests, i.e. biological effect monitoring. In such a case you need to know something about renal physiology and will need to read up the specific toxicology of the xenobiotic you are dealing with to ensure that there is useful way of monitoring early changes.

For example, testing the urine will only be useful if the xenobiotic causes a lesion which produces protein, blood or casts in the urine. Measuring serum creatinine as a marker of early effect is not possible because up to two thirds of renal function may be lost before serum creatinine starts to rise. You may thus find that there is no effective monitoring for early effect. (Remember the principle of medical surveillance. Don’t ask the question if you don’t know what to do with the answer.)

See the diagram.

ACUTE RENAL DISEASE:

Acute tubular necrosis:

Causes:

  1. Heavy metals:
  2. Solvents:
  3. Agrichemicals:

Clinical features:

Susceptibility: ? Alcoholism, mixed exposures.
Diagnosis: High index of suspicion needed.
Prognosis: Recovery often within 2 weeks.
Rx: Otherwise renal dialysis for acute renal failure

Special case: Acute tubular necrosis due to haemolysis

See the case study of acute renal failure.

Cause: Arsine gas (action of acid on metals containing arsenic). Unpredictable!
Presents: Immediate or delayed (24 hrs) acute illness with haematuria (actually haemoglobinuria)
Rx: Exchange transfusion
Prognosis: Recovery or chronic kidney disease

CHRONIC RENAL DISEASE:

Causes:

  1. LEAD: (Revise session on lead)

    Presentations:

    Clinical:

    Diagnosis:

    Treatment:

    Chelation in acute presentation. Role in chronic disease unknown - limited evidence for any efficacy. (See the Note on a South African study)

  2. CADMIUM:

    Sources:

    Metabolic effects: Tubules affected:

    Diagnosis/screening: Renal enzymes in urine

  3. MERCURY:

BLADDER CANCER (AND OF THE RENAL PELVIS, URETER OR URETHRA):

Estimated that 20% are work-related.

Otherwise, smoking most important preventable cause.

Main exposure: Dye/pigment manufacture or use; also textile manufacture