Regarding post-obstructive diuresis, which of the following is FALSE?
Answer C
POD in UUO with intact contralateral kidney may be because GFR is atypically preserved in the setting of distal tubular damage such that the kidney filters a normal volume but there is limited free water reabsorption. Or this can occur when a pronounced aquaporin channel defect may be present, causing diminished free water absorption in this setting. The diuresis after relief of obstruction is a normal physiologic response to the volume expansion and solute accumulation occurring during obstruction, wherein sodium, urea, and free water are eliminated and the diuresis subsides after solute and fluid homeostasis is achieved. Pathological postobstructive diuresis occurs due to derangement of the medullary solute gradient and downregulation of sodium transporters with subsequent impaired sodium reabsorption in the thick ascending limb of the Henle loop resulting in inappropriate renal handling of water or solutes. Moreover, this can also occur because of poor responsiveness of the collecting duct to antidiuretic hormone (ADH) probably due to a downregulation of aquaporin water channels in this segment of the nephron and perhaps in the proximal tubule.
Regarding retroperitoneal fibrosis (RPF), which of the following is FALSE?
Answer E
The development of vasculitis in the adventitial vessels leading to the release of antigens from atheromatous plaque such as ceroid, a complex lipoprotein, which induces an autoimmune antigenic response. The reported inflammatory conditions associated with RPF are IBD, ascending lymphangitis, asbestosis, amyloidosis and sarcoidosis. The classic radiologic findings of medial deviation of extrinsically compressed ureters can be demonstrated in up to 18% of normal subjects. CT reveals a well-defined mass, isodense with muscle in plain films. Tamoxifen is a nonsteroidal anti-oestrogen and is suggested to alter TGF-β, thereby limiting fibrosis. E. F. van Bommel reported a response rate of 74% in patients treated with Tamoxifen 20 mg OD for median duration of 8.5 months.
Which of the following is TRUE in hydronephrosis of pregnancy?
Answer B
The reported occurrence of hydronephrosis of pregnancy is between 43% and 100% (Faundes et al. 1998), the wide variation being due to different values used to report hydronephrosis. The right kidney becomes hydronephrotic two to three times more commonly than the left, probably because of interposition of sigmoid colon. Around one third of patients may have persistent hydronephrosis during the first postpartum week, but it resolves within 6 weeks in the majority. Despite the lack of solid evidence, MRI is not advocated in the first trimester of pregnancy (Leyendecker et al. 2004) and gadolinium contrast should be avoided in pregnant patients because it is known to cross the placental barrier. The presence of hydroureter upto the pelvic brim is readily apparent on T2 sequences and is characteristic of this condition. The majority of patients with symptomatic hydronephrosis of pregnancy can be managed with conservative measures. Rapid stent encrustation may be problematic, as urinary calcium excretion increases during pregnancy.
Which of the following is FALSE regarding biochemical pathology of urine in patients with kidney stones?
The concentration product, the point at which the dissolved and crystalline components are in equilibrium for a specific set of conditions, at the point of saturation is called the thermodynamic solubility product, Ksp. Inhibitors can generally prevent the process of crystal growth or aggregation above the formation product, Kf.
Which of the following is TRUE regarding biochemical pathology of urine?
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