14 CHAPTER 1 Preliminary investigation

Nocturia and nocturnal polyuria

Nocturia is the frequent need to get up and urinate at night. It is differentiated from enuresis (bed wetting) in that the person does not wake and the bladder empties.

Nocturnal polyuria (NP) refers to a condition in which the rate of urine output is excessive only at night and total 24-hour output is within normal limits.

Nocturia 2 is fairly common and is a bothersome cause of sleep disturbance.

Prevalence of nocturia 2: men—40% age 60–70 years, 55% age >70 years; women—10% age 20–40 years, 50% age >80 years.1,2 Nocturia 2 is associated with a 2-fold increased risk of falls and injury in the active elderly.

Men who void more than twice at night have a 2-fold increased risk of death, possibly due to the associations of nocturia with endocrine and cardiovascular disease.3

Diagnostic approach to the patient with nocturia

Nocturia can be due to urological disease, but more often than not it is nonurological in origin. Most awakenings from sleep attributed by patients pressured to urinate were instead a result of sleep disorders—even in those patients with well-known medical reasons for noctruria Therefore, “approach the lower urinary tract last” (Neil Resnick,4 Professor of Gerontology, Pittsburgh).5,6

Causes of nocturia

•Urological: benign prostatic obstruction, overactive bladder, incomplete bladder emptying

•Nonurological: renal failure, idiopathic nocturnal polyuria, diabetes mellitus, central diabetes insipidus, nephrogenic diabetes insipidus, primary polydipsia, hypercalcemia, drugs, autonomic failure, obstructive sleep apnea

Assessment of the nocturic patient

Ask the patient to complete a voiding diary that records time and volume of each void over a 24-hour period for 7 days. This establishes

•If the patient is polyuric or nonpolyuric

•If polyuric, is the polyuria present throughout 24 hours or is it confined to nighttime (nocturnal polyuria)?

1 Coyne KS, et al. (2003). The prevalence of nocturia and its effect on health-related quality of life and sleep in a community sample in the USA. Br J Urol Int 92:948–954.

2 Jackson S (199). Lower urinary tract symptoms and nocturia in women: prevalence, aetiology and diagnosis. Br J Urol Int 84:5–8.

3 McKeigue P, Reynard J (2000). Relation of nocturnal polyuria of the elderly to essential hypertension. Lancet 355:486–488.

4 Resnick NM (2002). Geriatric incontinence and voiding dysfunction. In Walsh PC, Retik AB, Vaughan ED, Wein AJ (Eds.), Campbell’s Urology, 8th ed. Philadelphia: W.B. Saunders.

5 Pressman MR, Figueroa WG, Kendrick-Mohamed J, et al. (1996). Nocturia. A rarely recognized symptom of sleep apnea and other occult sleep disorders. Arch Intern Med 156:545.

6 Fitzgerald MP, Litman HJ, Link CL; McKinlay JB, et al. (2007). The association of nocturia with cardiac disease, diabetes, body mass index, age and diuretic use: results from the BACH survey. J Urol 177:1385–1389.

NOCTURIA AND NOCTURNAL POLYURIA 15

Polyuria (24-hour polyuria) is defined as >3 L of urine output per 24 hours (standardization).

Nocturnal polyuria is defined as the production of more than one-third of 24-hour urine output between midnight and 8 a.m. (It is a normal physiological mechanism to reduce urine output at night. Urine output between midnight and 8 a.m.—one-third of the 24-hour clock—should certainly be no more than one-third of 24-hour total urine output and, in most people, will be considerably less than one-third.)

Polyuria (urine output of >3 L/24 hours) is due to either a solute diuresis or water diuresis.

Measure urine osmolality: <250 mosm/kg = water diuresis, >300 mosm/ kg = solute diuresis.

Excess levels of various solutes in the urine, such as glucose in the poorly controlled diabetic, lead to a solute diuresis. A water diuresis occurs in patients with primary polydipsia (an appropriate physiological response to high water intake) and diabetes insipidus (DI) (antidiuretic hormone [ADH] deficiency or resistance). Patients on lithium have renal resistance to ADH (nephrogenic DI).

Further reading

Guite HF, et al. (1988). Hypothesis: posture is one of the determinants of the circadian rhythm of urine flow and electrolyte excretion in elderly female patients. Age Ageing 17:241–248.

Matthiesen TB, Rittig S, Norgaard JP, Pedersen EB, Djurhuus JC (1996). Nocturnal polyuria and natriuresis in male patients with nocturia and lower urinary tract symptoms. J Urol 156:1292–1299.

van Kerrebroeck P, Abrams P, Chaikin D, et al. (2002). The standardisation of terminology in nocturia: Report from the Standardisation Sub-committee of the International Continence Society.

Neurourol Urodyn 21:179–183.

16 CHAPTER 1 Preliminary investigation

Flank pain

Sometimes referred to as loin pain, flank pain is pain or discomfort in the side of the abdomen between the last rib and the hip. It can present suddenly with the severity reaching a peak within minutes or hours (acute flank pain). Alternatively, it may have a slower course of onset (chronic flank pain), developing over weeks or months.

Traditionally, flank pain is presumed to be urological in origin, based on the anatomic position of the kidney and ureters. However, other structures in this region and pathology within these structures, and pain arising from extra-abdominal organs may radiate to the flank as a referred pain. While flank pain may be urological, other possibilities must be considered in the differential diagnosis.

The speed of onset of flank pain gives some, though not an absolute, indication of the cause of urological flank pain. Acute flank pain is more likely to be due to something obstructing the ureter, such as a stone. Flank pain of more chronic onset suggests disease within the kidney or renal pelvis.

Acute flank pain

The most common cause of sudden onset of severe pain in the flank is the passage of a stone formed in the kidney that is passing down through the ureter. Ureteric stone pain characteristically starts very suddenly (within minutes), is colicky in nature (waves of increasing severity are followed by a reduction in severity, though seldom going away completely), and radiates to the groin as the stone passes into the lower ureter.

The pain may change in location, from flank to groin, but its location does not provide a good indication of the position of the stone, except when the patient has pain or discomfort in the penis and a strong desire to void, which suggests that the stone has moved into the intramural part of the ureter (the segment within the bladder) or bladder. The patient cannot get comfortable and often changes position frequently without relief.

Half of patients with these classic symptoms of ureteric colic do not have a stone confirmed on subsequent imaging studies or have no documentation of passing a stone.1,2 They have some other cause for their pain (see next page).

A ureteric stone is only very rarely life threatening, but many of the differential diagnoses may be life threatening. Acute flank pain is less likely to be due to a ureteric stone in women and in patients at the extremes of age. Urolithiasis tends to be a disease of men (less common in women) between the ages of ~20 and 60 years, though it can occur in younger and older individuals.

1 Smith RC (1996). Diagnosis of acute flank pain: value of unenhanced helical CT. AJR Am J Roentgen 166:97–100.

2 Thomson JM (2001). Computed tomography versus intravenous urography in diagnosis of acute flank pain from urolithiasis: a randomized study comparing imaging costs and radiation dose.

Australas Radiol 45:291–297.

FLANK PAIN 17

Acute flank pain—non-stone, urological causes

•Clot or tumor colic: a clot may form from a bleeding source within the kidney (e.g., renal cell carcinoma or transitional cell carcinoma [TCC] of the upper urinary tract). A ureteral TCC may cause ureteric obstruction and acute flank pain. Flank pain and hematuria are often assumed due to a stone, but it is important to approach investigation of patients from the perspective of hematuria and to rule out cancer.

•Ureteropelvic junction obstruction (UPJO), also known as ureteropelvic junction obstruction (UPJO), may present acutely with flank pain severe enough to mimic a ureteric stone. A CT scan will demonstrate hydronephrosis, with a normal-caliber ureter below the PUJ and no stone. MAG3 renography usually confirms the diagnosis, demonstrating delayed emptying.

•Infection: e.g., acute pyelonephritis, pyonephrosis, emphysematous pyelonephritis, xanthogranulomatous pyelonephritis. These patients have a high fever (>38*C), whereas patients with a ureteric stone do not (unless there is associated infection) and are often systemically ill. Imaging studies may or may not show a stone, and there will be radiological evidence of infection within the kidney and perirenal tissues (such as edema or perinephric stranding on CT scan).

•Other less common causes include ptotic kidney, renal infarction or necrosis, renal vein thrombosis, calyceal diverticulum, renal cystic disease (medullary sponge kidney, hemorrhagic cysts), renal bleed (trauma or spontaneous from renal cell carcinoma or angiomyelolipoma), testicular torsion.

Acute flank pain—nonurological causes

Vascular

• Leaking or dissecting abdominal aortic aneurysm

Medical

•Pneumonia/pleurisy

•Myocardial infarction

•Malaria with bilateral flank pain and dark hematuria: “black water fever”

•Herpes zoster

Musculoskeletal

• Muscle spasm, sprain, flank hernia

Gynecological and obstetric

•Ovarian pathology (e.g., twisted ovarian cyst)

•Ectopic pregnancy

•Ovarian vein syndrome

Gastrointestinal

•Acute appendicitis

•Inflammatory bowel disease (Crohn’s, ulcerative colitis)

•Diverticulitis

•Perforated peptic ulcer

•Bowel obstruction

•Pancreatitis

18 CHAPTER 1 Preliminary investigation

Neurological/spinal

•Vertebral or spinal cord/nerve root irritation (bulging or herniated intervertebral disk, sciatica, tumor

•Vertebral body fracture or collapse

Distinguishing urological from nonurological flank pain

History and examination are most important. Patients with ureteric colic often move around the bed in extreme pain and are unable to find a comfortable position. Those with peritonitis lie still. With pancreatitis the patient gets relief with leaning forward.

Palpate the abdomen for signs of peritonitis (abdominal tenderness and/ or guarding) and examine for abdominal masses (pulsatile and bruit suggests aneurysm). In ovarian vein syndrome, pain can worsen on lying down or between ovulation and menstruation.

Examine the patient’s back, chest, and testicles. Costovertebral angle tenderness suggests a renal process or musculoskeletal process. In women, do a pregnancy test.

Urinalysis is critical as it suggests or excludes a urinary tract cause. However, up to 26% of patients with a documented stone on CT do not have hematuria.3,4

Chronic flank pain—urological causes

Renal or ureteric cancer

•Renal cell carcinoma

•Urothelial carcinoma of the renal pelvis or ureter

Renal stones

•Staghorn calculi

•Non-staghorn calculi, calyceal diverticular stone

Renal infection

•TB, fungal, malarial

•Chronic pyelonephritis, renal abscess

•Ureteropelvic junction obstruction

Testicular pathology (referred pain)

•Testicular neoplasms

•Testicular trauma

•Epidimo-orchitis

Ureteric pathology

•Ureteric reflux

•Ureteric stone (may drop into the ureter, causing severe pain which then subsides to a lower level of chronic pain)

3 Bove P, Kaplan D, Dalrymple N, et al. (1999). Reexamining the value of hematuria testing in patients with acute flank pain. J Urol 162:685–687.

4 Jindal G (2007). Acute flank pain secondary to urolithiasis: radiologic evaluation and alternate diagnoses. Radiol Clin North Am 45(3):395–410.

FLANK PAIN 19

Chronic flank pain—nonurological causes

Gastrointestinal

•Bowel neoplasms

•Liver disease

Spinal disease

•Prolapsed intervertebral disc

•Degenerative disease

•Spinal metastases