Portal de Periódicos da CAPES

Transient Acquired Fanconi Syndrome Associated with Copper Storage Hepatopathy in 3 Dogs

2008; Wiley; Volume: 22; Issue: 4 Linguagem: Inglês

10.1111/j.1939-1676.2008.0140.x

1939-1676

Elizabeth H. Appleman, Rachel E. Cianciolo, A.S. Mosenco, M.E. Bounds, S. Al‐Ghazlat,

Heavy Metal Exposure and Toxicity

Case 1: A 5-year-old female spayed Clumber Spaniel, 30.3 kg, was examined for a 3–4 day history of polyuria, polydipsia, lethargy, decreased appetite, and vomiting. Two months earlier, an increase in liver enzyme activity (alkaline phosphatase, ALP, 214 U/L, reference range 20–155 U/L) was documented, with no other abnormalities on the serum biochemistry panel. On presentation, there was a soft left apical systolic heart murmur ausculted. A serum biochemistry panel revealed increases in serum liver enzyme activities (alanine amino-transferase, ALT, 907 U/L, reference range 10–100 U/L; ALP, 344 U/L; aspartate amino-transferase, AST, 222 U/L, reference range 23–65 U/L) and creatinine concentration (2.4 mg/dL; reference range 0.5–1.4 mg/dL). A CBC was within reference range. Urinalysis indicated isosthenuria (specific gravity 1.008), proteinuria, and glucosuria; the serum glucose was within reference range. An aerobic bacterial culture of the urine yielded no growth. The urine protein : creatinine (UPC) ratio was increased at 1.2 (reference range < 0.5). Fanconi syndrome (FS) was confirmed through a urine metabolic profile (mild aminoaciduria, moderate glucosuria, and lactic aciduria).a Serum antibody titers for leptospirosis were increased (serovars grippotyphosa 1 : 800, icterohemorrhagicae 1 : 100); all other serovars were negative. An abdominal ultrasound showed mild hepatomegaly with bilateral hyperechoic renal cortices. Initial management consisted of administration of intravenous fluids (plasmalyte-Ab at 2 mL/kg/h), ampicillinc (22 mg/kg IV q8h), and esomeprazoled (1.0 mg/kg IV q24h). Two days later, hepatic and renal biopsies were obtained laparoscopically. No gross abnormalities were noted in either organ. Hepatic biopsy revealed moderate numbers of pigment-laden macrophages with admixed neutrophils surrounding central veins. Bands of fibrosis with associated lymphoplasmacytic inflammation often bridged multiple portal areas. Scattered singly apoptotic hepatocytes were seen. A rubeanic acid stain demonstrated copper-containing granules in most centrilobular hepatocytes (zone 3). With a previously published grading scale to semiquantify copper levels, a grade 3 out of 5 was given.e,1 A hepatic copper level was increased at 1,455 ppm (dry matter basis, DM, reference range 105–400 ppm). Features associated with leptospiral hepatitis, including piecemeal necrosis, hepatocellular dissociation, canalicular bile stasis, and increased numbers of mitoses, were not identified.2 Renal biopsy indicated numerous small eosinophilic granules within the cytoplasm of many proximal convoluted tubules, consistent with tubular protein resorption (see Fig 1). Unaffected proximal tubular epithelium often contained enlarged, plump nuclei that bulged into the lumen. A mild multifocal lymphoplasmacytic interstitial infiltrate with mild fibrosis was also identified. Rubeanic acid staining of the kidney did not reveal copper. A renal copper level was increased at 212 ppm DM (reference range 17.5–60 ppm). Diagnoses of copper storage hepatopathy with concurrent moderate chronic neutrophilic hepatitis, renal tubular dilation with karyomegaly, and interstitial nephritis were given. The dog was discharged 4 days after admission with initial therapy consisting of s-adenosyl-methioninef (SAMe, 22 mg/kg PO q24h), ursodeoxycholic acidg (UDCA, 10 mg/kg PO q24h), famotidineh (0.5 mg/kg PO q12h), and doxycyclinei (5 mg/kg PO q12h). Doxycycline was administered for 2 weeks. After completion of copper quantification, chelation was commenced with d-penicillaminej (10 mg/kg PO q24h). Needle biopsy of kidney from case 1, a Clumber Spaniel with Fanconi Syndrome. Note the dilated tubule lined by bulging karyomegalic epithelial cells. Adjacent tubule has small eosinophilic cytoplasmic granules (tubular protein reabsorption droplets). H&E stain, × 400, bar = 20 μm. Two months after presentation, the dog was clinically healthy with normal renal and hepatic parameters; resolution of FS was documented within 4 months. Follow-up hepatic and renal biopsies were not performed, nor were convalescent serum Leptospirosis antibody titers measured. The dosage of d-penicillamine was decreased (10 mg/kg PO q48h) and all other treatments withdrawn. Dog 2, a 6-year-old male castrated Cardigan Welsh Corgi, 16.6 kg, was examined for a 3-day history of decreased appetite, lethargy, polyuria, and polydipsia. One month before, liver enzyme activities were within reference range. Physical examination abnormalities included an increased rectal temperature (103.5°F) and hepatomegaly. A serum biochemistry panel revealed increased liver enzyme activities (ALT 1,155 U/L; AST 259 U/L). A CBC was within reference range. Urinalysis indicated proteinuria with a UPC of 1.5, coarse granular casts, a specific gravity of 1.024, and glucosuria; the serum glucose was normal. An aerobic bacterial culture of the urine yielded no growth. A urine metabolic profile was consistent with FS (carbohydrates 4+, moderate amino aciduria, small lactate, nitroprusside 2+).a Serum leptospirosis antibody titers tested negative. A diffusely mottled liver was visualized on abdominal ultrasound. Initial treatment consisted of administration of intravenous fluids (plasmalyte-Ab at 4 mL/kg/h) and antibiotics (ampicillinc 22 mg/kg IV q8h; metronidazolek 7.5 mg/kg IV q12h). Three days later, liver biopsies were obtained laparoscopically; a renal biopsy was not performed. Hepatic histopathology showed central veins surrounded by numerous pigment-laden macrophages and neutrophils (see Fig 2). Singly dead hepatocytes were scattered throughout the inflammatory foci. A rubeanic acid stain showed copper-containing granules within the cytoplasm of most centrilobular to midzonal hepatocytes (zones 2–3, see Fig 3). Additionally, copper granules were identified in the pigment-laden macrophages (semiquantitative copper grade 4).e Hepatic aerobic and anaerobic bacterial cultures yielded no growth. The hepatic copper concentration was markedly increased at 3,290 ppm DM. A diagnosis of copper storage hepatopathy with concurrent severe chronic neutrophilic hepatitis was given. Wedge biopsy of liver from case 2, a Cardigan Welsh Corgi with copper-associated chronic hepatitis. Pigment-laden macrophages and neutrophils surround central veins. Centrilobular hepatocytes (zone 3) contain red-brown pigment. H&E stain, × 400, bar = 20 μm. Wedge biopsy of liver, case 2. Note the centrilobular hepatocytes with numerous cytoplasmic green-blue copper granules. Rubeanic acid stain, × 400, bar = 20 μm. The dog was discharged 5 days after admission with initial therapy consisting of SAMef (20 mg/kg PO q24h), d-penicillaminej (15 mg/kg PO q12h), and Hills L/D diet.l Three months after hospital discharge, the dog was clinically healthy with normal hepatic parameters and resolution of glucosuria. Follow-up hepatic and renal biopsies were not performed. Current therapy includes d-penicillamine and Hills L/D diet. Dog 3, a 13-year-old male castrated West Highland White Terrier, 7 kg, was examined for a 3–4 day history of vomiting and diarrhea. One month before, a CBC and serum biochemistry panel were unremarkable. On physical examination, the dog was lethargic and icteric. A serum biochemistry panel revealed increases in bilirubin (5.5 mg/dL, reference range 0.0–0.2 mg/dL), creatinine (2.5 mg/dL), and liver enzyme activities (ALT 799 U/L, ALP 1,219 U/L); a CBC was within reference range. Urinalysis indicated a specific gravity of 1.021, ketonuria, proteinuria, bilirubinuria, and glucosuria; the serum glucose was normal. An aerobic bacterial culture of the urine yielded no growth. A UPC ratio was increased at 2.2. Analysis of the urine was consistent with FS (severe amino aciduria, moderate lactate, and large glucose).a Serum leptospirosis antibody titers were negative. Abdominal ultrasound showed a hyperechoic liver and a distended gall bladder. The dog was treated with ampicillinc (22 mg/kg IV q8h) and metronidazolek (7.5 mg/kg IV q12h). A serum biochemistry panel showed worsened liver parameters (bilirubin 17.1 mg/dL, ALP 1,960 U/L, ALT 619 U/L). Exploratory surgery was performed, revealing a diffusely mottled and discolored liver. The gallbladder was easily expressed with no evidence of biliary obstruction. All other organs appeared normal. The dog's bilirubin improved after surgery but then rose rapidly, reaching a maximum of 37 mg/dL within 3 days. Clinically, the dog exhibited anxiety, pacing, and facial tremors; an ammonia level was normal at that time (9 μmol/L; reference range 11–35 μmol/L). Repeat abdominal ultrasound showed a similarly sized gall bladder with no distension of the biliary ducts. As compared to dogs 1 and 2, hepatic histopathology revealed similar but more severe centrilobular inflammation. Additionally, there was focally extensive hepatocellular loss resulting in expansion of preexisting sinusoids (telangiectasia) with numerous pigment granulomas and associated portal-portal bridging fibrosis. The remainder of the sample contained scattered singly dead hepatocytes, multifocal pigment granulomas, numerous canalicular bile plugs, and multifocal extramedullary myelopoeisis. Although the histiocytic and neutrophilic hepatitis was severe, hepatocellular copper was limited to numerous granules within centrilobular hepatocytes (zone 3) and pigment-laden macrophages (rubeanic acid stain, semiquantitative copper grade 3).e In the kidney, moderate segmental acute tubular necrosis with associated intracellular orange-green pigment was seen. Specifically, necrotic cells contained pyknotic or karyorrhectic debris with hypereosinophilic, vacuolated cytoplasm. Numerous proximal tubular epithelial cells were also characterized by karyomegaly without other evidence of tubular regeneration. These karyomegalic cells often bulged into the empty, dilated tubular lumen, as described previously in canine FS.3 Rubeanic acid stain for the kidney was negative; therefore, the orange-green pigment was interpreted as bile. Aerobic and anaerobic bacterial cultures from bile and liver parenchyma yielded no growth. A hepatic copper concentration was increased at 2,180 ppm DM, confirming a diagnosis of copper storage hepatopathy with concurrent severe chronic neutrophilic hepatitis. Initial therapy included UDCAg (10 mg/kg PO q24h), d-penicillaminej (10 mg/kg PO q12h), and dexamethasone sodium phosphatem (0.2 mg/kg IV q12h). The bilirubin dropped from 37 to 2.8 mg/dL over 6 days. Despite the improvement in hepatic parameters, the dog's neurologic signs persisted. The dog was discharged 10 days after admission; medications included prednisonen (1 mg/kg PO q12h), UDCA, omeprazoleo (1 mg/kg PO q24h), and d-penicillamine. The dog's neurologic abnormalities resolved at home several weeks after hospital discharge. Prednisone was tapered over 2 months. At a 2 month follow-up, the dog's creatinine, bilirubin, and urinalysis had normalized, though increases in ALP (827 U/L) and ALT (256 U/L) activities persisted. Follow-up hepatic and renal biopsies were not performed. Current therapy includes d-penicillamine and omeprazole. This report describes an acute onset of copper storage hepatopathy and concurrent transient acquired FS in 3 dogs. FS is a rare disorder in veterinary medicine, characterized by impaired proximal tubular reabsorption of bicarbonate, glucose, amino acids, water, and other electrolytes. Pathogenesis of canine FS may be idiopathic or acquired.4 An idiopathic familial etiology is suspected in the Basenji breed,5 whereas the acquired form is often transient and associated with other diseases. The clinical course of idiopathic FS appears variable. In 1 study, Basenjis had a median survival time of 5.25 years following diagnosis of FS; most of these dogs were aggressively treated with bicarbonate and potassium supplementation to minimize acid-base abnormalities and electrolyte deficiencies.5 However, a graver prognosis has been documented in other breeds, with dogs surviving <5 months after the initial diagnosis of FS.6-8 Diseases associated with the transient acquired form of canine FS include primary hypoparathyroidism, proximal renal tubular acidosis, drug- or toxin-induced injury, and systemic hypertension.3, 4, 9 Similar to the cases presented here, the proximal renal tubular function of dogs in the veterinary literature with transient acquired FS normalized within weeks to months after supportive care or specific therapy for the associated disease.3, 4, 9 The ability to treat any associated, and possibly underlying, disease may allow prompt resolution of acquired FS and prevention of chronic renal damage. Hepatic disease has been directly associated with dysfunction of the proximal renal tubules. The presence of glucosuria with normoglycemia was documented in several Dalmatians with confirmed copper storage hepatopathies, though screening for FS and renal histopathology were not performed.10 Another report described transient acquired FS in a Labrador Retriever with increased liver enzyme activities.3 Recently, a West Highland White Terrier was diagnosed with concurrent transient FS and copper storage hepatopathy.11 That case has similarities to the dogs reported here, including histopathologic abnormalities, presumed resolution of FS, and a favorable prognosis. Copper storage hepatopathies have been diagnosed in a variety of breeds, including the West Highland White Terrier, Doberman Pinscher, Labrador Retriever, and Bedlington Terrier.12 Excess hepatic copper can accumulate from a primary defect in hepatic copper metabolism or secondary to a cholestatic-induced decrease in biliary copper excretion.12 Differentiation between a primary versus secondary etiology of copper accumulation can be challenging, because histopathology often shows the presence of hepatic fibrosis, inflammation and cirrhosis regardless of inciting cause.12 In these dogs, the midrange semiquantitative copper scores (grade ≥ 3) and copper levels in the liver did not clearly demarcate either a primary or secondary etiology for copper accumulation.1, 12 There is stronger evidence for a primary copper hepatopathy in case 3, because West Highland White Terriers are believed to have a hereditary copper storage defect.13 The severity and progression of hepatic damage differed among the 3 cases, though their associated FS remained clinically mild. Resolution of FS and copper storage hepatopathy was presumed based on normalization of clinical signs, serial biochemical screens, and urinalyses. Dog 1 may have had a concurrent leptospirosis infection in addition to copper storage hepatopathy. However, this dog's hepatic and renal histopathology had features that are not consistent with leptospirosis-induced damage.2 Clinical signs and biochemical parameters in dog 1 did not resolve until copper chelation commenced, despite early administration of antimicrobials. For dog 3, the persistent increases in liver enzyme activities, ALP and ALT, were attributed to steroid isoenzyme induction and steroid hepatopathy. Other possible causes of increased liver enzyme activities in this dog include a persistent copper-induced hepatopathy and/or chronic hepatitis. These 3 cases resemble Wilson's disease (WD) with respect to their transient FS and its resolution following copper chelation therapy. WD is a rare autosomal recessive disorder of human copper metabolism that can be associated with FS.14 Disease progression causes excessive copper to be deposited primarily in the liver, brain, and kidneys.15 Hepatic histopathology may reveal fatty changes, periportal inflammation, lobular necrosis, or bridging fibrosis. Histochemical confirmation of excess copper, which typically accumulates periportally, is often used to confirm a diagnosis.16, 17 Neurologic abnormalities, possibly caused by the toxic effects of copper accumulation in the brain, are present in 40–50% of patients with WD.18 Dog 3's neurologic signs are similar to those seen in people with WD and resolved within several weeks of commencing copper chelation. However, other causes for the dog's signs, such as primary intracranial disease or hepatic encephalopathy, were not excluded. Renal pathology in humans with WD is characterized by copper deposition in the proximal renal tubular cells, causing vacuolar degeneration and subsequent FS14; renal copper content can be significantly increased.18 In dog 1, a renal copper level was increased more than 3 times the normal range. Renal copper concentration was not quantified for dog 3. Abnormal copper accumulation in the renal tubular epithelium (by a rhodanine staining technique) was documented in another dog with a similar syndrome.11 In humans, the absence of increased copper content in the liver and kidney does not exclude a diagnosis of WD.14 Possible explanations include early disease progression, nonuniform copper deposition throughout the affected parenchyma,19 or diffuse distribution of copper in the cellular cytoplasm that does not stain.20 This may account for the negative rubeanic acid stain in the kidney of dogs 1 and 3. In addition to copper-mediated renal tubular damage, hyperbilirubinemia may also be involved, specifically in case 3. Although bile has not been demonstrated to be directly toxic to canine renal tubules, it is associated with hypotension and cardiodepression in people.21 Renal tubular damage in these scenarios is often attributed to ischemia. The association of hepatic disease and concurrent FS underscores the relationship between impaired hepatic excretion of toxins (ie, heavy metals) and damage of proximal convoluted tubules. Further renal biopsies are needed to determine the cause of FS in canine copper storage hepatopathies. In summary, this report documents copper storage hepatopathy with concurrent transient acquired FS in 3 dogs. These dogs had an excellent prognosis, with presumed resolution of both copper storage hepatopathy and FS. To the authors' knowledge, there are no reports of copper storage hepatopathies either in the Clumber Spaniel or in the Cardigan Welsh Corgi. The combination of acute hepatic disease with acquired FS should raise the suspicion for this atypical presentation of copper storage disease. Future studies are needed to evaluate the prevalence and etiology of FS in dogs with copper storage hepatopathy and to determine if this association has any diagnostic and/or prognostic value. aTesting for urine metabolic profiles performed by the Metabolic Genetic Disease Testing Laboratory, School of Veterinary Medicine, University of Pennsylvania bPlasmalyte-A, Baxter Healthcare Corp, Deerfield, IL cAmpicillin inj, Sandox GMBH, Princeton, NJ dNexium IV, Astrazeneca LP, Wilmington, DE e0, no copper; 1, solitary liver cells and/or reticulohistiocytic (RHS) cells containing some copper positive granules; 2, small groups of liver cells and/or RHS cells containing small to moderate amounts of copper positive granules; 3, larger groups or areas of liver cells and/or RHS cells containing moderate amounts of copper positive granules; 4, large areas of liver cells and/or RHS cells with many copper positive granules; 5, diffuse presence of liver cells and/or RHS cells with many copper positive granules fDenosyl, Nutramax Laboratories Inc, Edgewood, MD gUrsodiol, Watson Laboratories, Corona, CA hPepcid AC, PAR Pharmaceutical Companies Inc, Spring Valley, NY iDoxycycline Hyclate Tablets USP, Major Pharmaceuticals, Livonia, MI jCuprimine, Merck & Co Inc, Whitehouse Station, NJ kMetronidazole Inj USP, Hospira Inc, Lake Forest, IL lHills L/D, Hills Pet Nutrition Inc, Topeka, KS mDexamethasone Sodium Phosphate, American Reagent Inc, Shirley, NY nPrednisone, Roxane Laboratories Inc, Columbus, OH oPrilosec OTC, Procter & Gamble, Cincinnati, OH All patients were treated at the Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania, Philadelphia, PA.