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19 CASE 19


A 45-year-old man comes to the emergency department complaining of severe pain on his right flank.


There is no evidence of injury. The patient has been working in the yard all day and appears dehydrated. He is capable of providing a small volume of urine for analysis.



PHYSICAL EXAMINATION



VS: T 38°C, P 100/min, R 22/min, BP 130/100 mm Hg

PE: The patient describes the colicky pain that has a sudden onset. On examination, the pain is localized to the flank area, particularly with pressure. During the examination, the patient appears extremely restless and unable to find a comfortable position.


LABORATORY STUDIES



Urinalysis: Urine pH is 4.3 and osmolality is 1200 mOsm/L. Abnormal findings include microscopic hematuria (red blood cells) and small calcium oxalate crystals (kidney stones).

Noncontrast spiral CT scan: Stone in the right kidney


DIAGNOSIS


Kidney stones



COURSE


The patient received 1 L of 0.45% saline and additional water to drink. He was given ketorolac for pain management. He was sent home with instructions to drink lots of fluids until the kidney stone passes and to take Vicodin as needed for pain. He is to pass urine through a strainer and bring in any excreted stones to be sent to the pathology laboratory.



PATHOPHYSIOLOGY OF KEY SYMPTOMS


Fluid balance within the body requires adjusting accumulation, through ingestion and metabolism, against elimination in the urine, feces, breath, skin, and sweat. Excessive sweating in the absence of additional water ingestion results in dehydration, characterized by a decrease in both the extracellular and cell water stores (Fig. 19-1).


image

FIGURE 19–1 Body water balance requires the regulation of intake (thirst) and renal excretion to compensate for the unregulated loss of water through respiration and sweating.


Although sweat does contain NaCl, sweat is hypotonic compared with plasma. Consequently, excessive sweating results in an increase in osmolality in the body fluid compartments. The increase in osmolality stimulates the release of antidiuretic hormone (ADH, vasopressin) from the posterior pituitary. ADH increases the permeability of the distal tubule and collecting duct to water and urea and results in the production of a very small volume of highly concentrated urine. In this patient, the urine osmolality of 1200 mOsm/L is close to the maximum urine concentrating ability (Fig. 19-2).


image

FIGURE 19–2 Changes in osmolarity of the tubular fluid as it passes through the different tubular segments in the presence of high levels of antidiuretic hormone (ADH) and in the absence of ADH. (Numerical values indicate the approximate volumes in milliliters per minute of fluid flowing along the different tubular segments.)

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Jul 4, 2016 | Posted by in PHYSIOLOGY | Comments Off on 19

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