Urine testing abnormalities (ILO/IMO Guidelines Appendix E R 31,18,82)

Background

Urine testing, normally by dipstick, forms an essential part of the medical assessment. The rationale for this is as an indicator of kidney and other disease and that positive findings require certification of temporary unfitness until fully investigated, with their causes resolved. Recent studies and reviews indicate that the excess risk of serious or sudden illness after some sorts of positive results is very low and cessation of routine testing for blood and protein has even been advocated. In medical fitness assessment simple urine testing can still be justified as the pressures to obtain and retain work may be sufficient to mean that past urinary tract or other disease is not otherwise disclosed. Recent general recommendations about follow up to positive urine tests enable the requirements for investigation and determination of cause to be specified in more detail for seafarers and in a way which will enable many to return to sea immediately. In the case of recruits, the low rate of abnormality associated with findings of trace proteinuria or haematuria mean that these findings, without any other signs or symptoms are not a reason for failure.

Notes:

1. These recommendations are based on the pattern of medical conditions in seafarers from North Western Europe. Where there is a different national pattern of renal and urinary tract disease, for instance a high incidence of renal calculi or parasitic infections, then local criteria for investigation should be followed.
2. The guidance only relates to decision taking about fitness to work at sea. If abnormal results are found on any test it will normally be appropriate to either advise the seafarer to see their general practitioner or to write them a letter stating the result.

HAEMATURIA - Impairment and risk

May be an indicator of the potential for a medical emergency at sea from renal colic or from recurrence of urinary tract infection. May identify longer term risk from the development of a urinary tract cancer.

• Dipstick tests are highly sensitive and there are only weak links between positive findings and subsequent disease. The extrapolation of prognosis from visible to dipstick haematuria is not justified. Haematuria can be present in urinary tract infection, with calculi, from prostatic disease or from a carcinoma of the urinary tract. Blood may also be present in a urine sample from menstruation or from minor lower tract trauma.
• Detection of urinary tract cancers based on detailed investigation of all cases of dipstick haematuria does not appear to improve prognosis as compared with action taken when they first present with visible haematuria or other signs.
• Haematuria associated with proteinuria, even at quite low levels, can be an indicator of early glomerular disease.

 PROTEINURIA - Impairment and risk

Proteinuria may be an indicator of kidney pathology. In this case there is a risk of progressive kidney failure. This may lead to illness at sea. It may also indicate that the kidney has less than the normal ability to deal with dehydration or fluid overload.

Rationale and justification

• The dipstick tests for protein are very sensitive. Levels +++ are likely to indicate significant renal or metabolic problems, lower levels are rarely indicative of serious pathology. The presence of both haematuria and proteinuria together can be an indicator of the early stages of glomerular disease.
• The presence of casts on urine microscopy increases the likelihood that the proteinuria (with or without haematuria) is an indicator of renal pathology. The ratio of protein to creatinine is an indicator of whether there is a normal pattern of urinary excretion from the kidney. The laboratory used can advise on reference values.
• The presence of semen or vaginal fluids and urinary tract infection can all lead to the detection of protein in the urine.
• The presence of proteinuria + + + indicates a risk in the short term from depletion of protein or from the presence of severe renal damage.
• Progression from minor degrees of kidney impairment to serious kidney disease that could lead to an emergency at sea does not always occur and when it does it normally takes place over a period of several years. Progression can be monitored.

GLYCOSURIA - Impairment and risks

Glycosuria is a common presenting feature of diabetes (see ILO/IMO Guidelines Appendix E E10-14) . The risks are those of the condition. Untreated it may indicate a short term risk of diabetic keto-acidosis and coma.

Rationale and justification

• Glycosuria occurs when the threshold for glucose re-absorption by the kidney has been exceeded. It is not as reliable a way of screening for diabetes as measuring fasting blood glucose or looking at the effects of an acute glucose load on blood and urine levels.
• The presence of glycosuria in a person with diabetes indicates that the control of their blood glucose levels is poor and their treatment needs reviewing.
• The presence of ketones on dip stick testing indicates that changes that are a consequence of altered glucose metabolism are present.

Decision trees

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