Renal vein Thrombosis

Objective Background Causes Presentation Diagnosis Treatment

Background Renal vein thrombosis (RVT) has numerous etiologies, it occurs most commonly in patients with nephrotic syndrome. The syndrome is responsible for a hypercoagulable state. The excessive urinary protein loss is associated with decreased antithrombin III, a relative excess of fibrinogen

Pathophysiology Hypercoagulability is the etiology for both arterial and venous thromboses. In the setting of malignant invasion of the vein by cancer, the presence of the tumor cells elicits thrombosis of the renal vein only. It may also occur as the result of blunt trauma to the abdomen or back. In infants, renal vein thrombosis can be associated with dehydration

Causes Nephrotic syndrome Antithrombin III deficiency, protein C or S deficiency, antiphospholipid antibody syndrome, Pregnancy or estrogen therapy. Renal vein invasion by malignant cells, Postrenal transplantation, Behçet syndrome, SLE. Extrinsic compression (e.g. lymph nodes, tumor, retroperitoneal fibrosis, aortic aneurysm). Trauma.

Presentations Could be asymptomatic. The clinical manifestations depend on the severity and abruptness of its occurrence. Acute cases occur typically in children and are characterized by sudden loss of renal function, often accompanied by fever, chills, lumbar tenderness (with kidney enlargement), leukocytosis, and hematuria. RVT is a potential cause of early graft dysfunction following renal transplantation.

Diagnosis Urine protein and loss renal function studies Serum complement levels In renal vein thrombosis (RVT), an intravenous pyelogram (IVP) with an abdominal plain film may reveal an enlarged kidney. Inferior vena cavography may help provide a diagnosis of renal vein thrombosis (RVT).

Diagnosis The definitive diagnosis can only be established through selective renal venography Renal arteriography may be useful in situations in which renal vein thrombosis (RVT) is secondary to trauma or tumor, in which case renal artery involvement is common.

Renal ultrasound is a safe noninvasive technique Renal ultrasound is a safe noninvasive technique. Ultrasound is usually not sensitive enough to assist in making the diagnosis. CT scan currently is the procedure of choice for diagnosing renal vein thrombosis (RVT) noninvasively.

Treatment Treatment of underlying cause. Symptomatic treatment includes diuretics and angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) to decrease proteinuria from nephrotic syndrome. Treat hypercholesterolemia if present

Anticoagulation with warfarin has been recommended in some studies for prophylaxis against pulmonary embolism. Warfarin, ARBs, and ACEIs are unsafe in pregnancy. Patients with renal vein thrombosis (RVT) in pregnancy are treated best with heparin alone.

Encouraging reports have appeared concerning the use of streptokinase. Nephrectomy is advocated in infants with life-threatening renal infarction. Percutaneous mechanical thrombectomy is effective in some cases.

Surgical treatment for renal vein thrombosis (RVT) is rarely used today. Surgery has been used in the presence of bilateral renal vein thrombosis (RVT) or if pulmonary emboli have occurred and anticoagulation is contraindicated.

Renal Tubular Acidosis

Objectives Definition. Types and Causes Presentation. Complications and Treatment. Prevention

Definition Renal tubular acidosis (RTA) is a disease that occurs when the kidneys fail to excrete acids into the urine, which causes a person's blood to remain too acidic. Healthy kidneys help maintain acid-base balance by excreting acids into the urine and returning bicarbonate.

Types Type 1: Classical Distal RTA. Type 2 (Proximal) RTA Type 3 Type 4: Hyperkalemic RTA

Type 1: Classical Distal RTA. Causes: Congenital Hyperglobulinaemia, Autoimmune connective tissue diseases, e.g. SLE Toxins and drugs, e.g. toluene, lithium, amphotericin

Clinical Features and Diagnosis In primary distal RTA (dRTA), the kidneys are unable to acidify the urine to pH <5.5 in the presence of systemic metabolic acidosis. Other features are hypokalemia, hypocitraturia, hypercalciuria, nephrocalcinosis, and/or nephrolithiasis. Chronic untreated acidosis may cause rickets or osteomalacia. Inheritance of primary dRTA includes autosomal dominant and autosomal recessive forms with a broad spectrum of clinical expression.

Autosomal recessive dRTA most often presents in infancy. Many patients with autosomal dominant dRTA, and some with recessive disease, are asymptomatic, and RTA is discovered incidentally in adolescence or adulthood during evaluation for kidney stones.

Treatment Early initiation of alkali replacement at doses equivalent to 1–3 mmol/kg/day of bicarbonate in divided doses will usually correct the acidosis, hypokalemia, and hypocitraturia, maintaining growth and preventing bone disease in early-onset dRTA. Citrate is generally tolerated better than sodium bicarbonate and can be given as potassium or sodium salt, depending on the severity of hypokalemia.

Treatment In patients who present later with kidney stones, large fluid intake and sufficient alkali to restore normal acid-base balance corrects the hypocitraturia and reduces hypercalciuria, thereby inhibiting the formation of new stones.

Type 2 (Proximal) RTA Is the result of impaired bicarbonate reabsorption in the proximal tubular. It is most often secondary to various autoimmune, drug-induced, infiltrative, or other tubulopathies or a result of tubular injury from inherited diseases.

Type 2 (Proximal) RTA Causes: Congenital, e.g. Fanconi's syndrome, cystinosis, Wilson's disease Paraproteinaemia, e.g. myeloma Amyloidosis Hyperparathyroidism Heavy metal toxicity, e.g. Pb, Cd, Hg Drugs, e.g. carbonic anhydrase inhibitors, ifosfamide

Features are hyperchloremic acidosis, rickets or osteomalacias are the predominant effects of Fanconi syndrome. It is difficult to restore normal acid-base balance despite large amounts of alkali. When the serum bicarbonate is raised above the threshold with alkali therapy, bicarbonate wasting recurs and causes hypokalemia by flooding the distal nephron with a nonreabsorbable anion. Treatment of pRTA requires 5–15 mmol/kg/day of bicarbonate together with supplementation of potassium and vitamin D.

Type 3 Type 3 is rarely used as a classification because it is now thought to be a combination of type 1 and type 2.

Type 4: Hyperkalemic RTA Causes: Hypoaldosteronism (primary or secondary) Obstructive nephropathy Drugs, e.g. amiloride, spironolactone, Trimethoprime. Renal transplant rejection

The transport of electrolytes such as sodium, chloride, and potassium that normally occurs in the distal tubule is impaired. This form is distinguished from classical distal RTA and proximal RTA because it results in high levels of potassium in the blood instead of low levels.

Treatment Hyperkalemia is treated with volume expansion, dietary K restriction, and K-wasting diuretics (eg, furosemide20 to 40 mg po once/day or bid titrated to effect). Alkalinization is often unnecessary. A few patients need mineralocorticoid replacement therapy (fludrocortisone).