Chapter 146: Renal Tubular Disease

Tubulointerstitial diseases constitute a diverse group of acute and chronic, hereditary and acquired disorders involving the renal tubules and supporting structures (Table 146-1). Functionally, they may result in a wide variety of physiologic phenotypes, including nephrogenic diabetes insipidus (DI) with polyuria, non-anion-gap metabolic acidosis, salt wasting, and hypo- or hyperkalemia. Azotemia is common, owing to associated glomerular fibrosis and/or ischemia. Compared with glomerulopathies, proteinuria and hematuria are less dramatic, and hypertension is less common. The functional consequences of tubular dysfunction are outlined in Table 146-2.

TABLE 146-1: Principal Causes of Tubulointerstitial Disease of the Kidney
Toxins
Exogenous toxins	Metabolic toxins
Analgesic nephropathy^a	Acute uric acid nephropathy
Lead nephropathy	Gouty nephropathy^a
Chinese herb nephropathy	Hypercalcemic nephropathy
Balkan endemic nephropathy	Hypokalemic nephropathy
Miscellaneous nephrotoxins (e.g., antibiotics, cyclosporine, radiographic contrast media, heavy metals)^a,b	Miscellaneous metabolic toxins (e.g., hyperoxaluria, cystinosis, Fabry’s disease)
Neoplasia
Lymphoma
Leukemia
Multiple myeloma (cast nephropathy, AL amyloidosis)
Immune Disorders
Acute (allergic) interstitial nephritis^a,b	Transplant rejection
Sjögren’s syndrome	HIV-associated nephropathy
Amyloidosis
Vascular Disorders
Arteriolar nephrosclerosis^{^a}	Sickle cell nephropathy
Atheroembolic disease	Acute tubular necrosis^{^a,b}
Hereditary Renal Diseases
Disorders associated with renal failure	Hereditary tubular disorders
Autosomal dominant polycystic kidney disease	Bartter’s syndrome (hereditary hypokalemic alkalosis)
Autosomal recessive polycystic kidney disease	Gitelman’s syndrome (hereditary hypokalemic alkalosis)
Medullary cystic kidney disease Hereditary nephritis (Alport’s syndrome)	Pseudohypoaldosteronism type I (hypotension/salt wasting and hyperkalemia)
	Pseudohypoaldosteronism type II (hereditary hypertension and hyperkalemia)
	Liddle’s syndrome (hypertension and hypokalemia)
	Hereditary hypomagnesemia
	Hereditary nephrogenic diabetes insipidus
	X-linked (AVP receptor dysfunction)
	Autosomal (aquaporin-2 dysfunction)
Infectious Injury
Acute pyelonephritis^a,b
Chronic pyelonephritis
Miscellaneous Disorders
Chronic urinary tract obstruction^a
Vesicoureteral reflux^a
Radiation nephritis

^aCommon.

^bTypically acute.

TABLE 146-2: Transport Dysfunction in Tubulointerstitial Disease
DEFECT	CAUSE(S)
Reduced GFR^a	Obliteration of microvasculature and obstruction of tubules
Fanconi syndrome	Damage to proximal tubular reabsorption of solutes, primarily glucose, amino acids, and phosphate; may also exhibit hypouricemia, proximal tubular acidosis, low-molecular-weight proteinuria
Hyperchloremic acidosis^a	1. Reduced ammonia production (CKD) or excretion (hyperkalemia)
	2. Inability to acidify the collecting duct fluid (distal renal tubular acidosis)
	3. Proximal bicarbonate wasting (proximal RTA)
Polyuria, isothenuria^a	Damage to medullary tubules (thick ascending limb and/or collecting duct) and vasculature
Hypokalemic alkalosis	Damage or hereditary dysfunction of the thick ascending limb or distal convoluted tubule (Bartter’s and Gitelman’s syndromes)
Magnesium wasting	Damage or hereditary dysfunction of the thick ascending limb or distal convoluted tubules
Hyperkalemia^a	Potassium secretory defects including aldosterone resistance
Salt wasting	Distal tubular damage with impaired sodium reabsorption

^aCommon.

Abbreviations: CKD, chronic kidney disease; RTA, renal tubular acidosis.

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