Renal Investigations

Question 1

What instructions should you give to a male and female patient for urine collection?

Answer 1

Female: We need a mid-stream urine, meaning you release some urine first and collect the stream in the middle. This is to prevent contamination.

Male: Please retract the foreskin and collect the mid-stream urine, meaning…

Question 2

In children or adults who are unable to provide a MSU sample what alternate way can you collect the sample?

Answer 2

Suprapubic aspiration

Question 3

Foamy or frothy urine (like coffee foam) indicates what?

Answer 3

Proteinuria

Question 4

Conjugated hyperbilirubinemia will cause urine to turn into what colour?

Answer 4

excessively yellow

Question 5

Excess urobilinogen in urine will cause urine to turn into what colour?

Answer 5

Orange colour

Question 6

What is the upper limit of proteinuria? How much protein in 24 hr urine sample?

Answer 6

> 128mg/24hr of protein in the urine is considered proteinuria

Question 7

What can cause urine to be excessively alkaline (pH)?

Answer 7

If infected with bacteria that splits urea and urea is alkaline

Question 8

Normal urine is acidic. However when is alkaline urine desirable? When need to excrete….

Answer 8

Excrete excess globin and crystals by forced alkaline diuresis since these stuff dissolve better in alkaline urine.

• Haemoglobinuria - tumour lysis
• Myoglobinuria - rhabdomyolysis
• Urate nephropathy, cystinuria

Question 9

What supplement can cause a false negative when the patient actually has glycosuria?

Answer 9

Consuming too much Vitamin C

Question 10

What urine sample should be taken to check for specific gravity?

Answer 10

Early morning urine that is concentrated

Question 11

What problem does a low specific gravity suggest? Urine too diluted…

Answer 11

Concentrating problem

Question 12

Proteinuria and glycosuria will cause the specific gravity to ____

Answer 12

Be high

Question 13

An early morning concentrated urine sample should have a specific gravity more than what?

Answer 13

1.024

Question 14

What can a positive nitrite stick test detect? What bacteria do not produce positive pink nitrite test?

Answer 14

Nitrite-forming bacteria, which are most common urinary pathogens
Except for pseudomonas, some staph and strep faecalis

Question 15

What can a urine leukocyte esterase test detect?

Answer 15

Infection - presence of urinary leukocytes

Question 16

Dysmorphic and isomorphic RBCs in the urine can help to differentiate between which types of bleeding?

Answer 16

Dysmorphic - glomerular bleeding

Isomorphic - non-glomerular bleeding e.g. from the bladder

Question 17

Ix of urine volume: what are some causes of polyuria?

Answer 17

• CKD
• Diabetes insipidus
• Glycosuria

Question 18

Urine osmolality and specific gravity is useful in investigating what?

Answer 18

• Oliguric renal failure
• Investigate polyuria
• Inappropriate ADH secretion

Question 19

CKD and ATN usually results in a specific gravity of what?

Answer 19

Fixed at 1.010

Question 20

Specific gravity is usually high in what renal diseases?

Answer 20

Pre-renal AKI

Inappropriate ADH secretion

Question 21

What investigations to order for a patient with bilaterally enlarged kidneys?

Answer 21

1. FBC
2. UEC: Ca (iPTH), PO4, uric acid
3. Urinalysis
4. Renal U/S (cysts - Ravine’s criteria for APKD)
5. CT / MRI
6. Genetic testing
7. MRA (intracranial anuerysm), echocardiogram (if murmur present; LVH, valvular), barium enema (diverticulosis)