Kidneys in Systemic Disease Flashcards
When should you think of a systemic disease?
-Fever, night sweats
-Weight loss, anorexia, fatigue
-Arthralgia, myalgia, joint swelling
-Skin rash, nodules
-Eye inflammation
-Breathlessness, haemoptysis
-Symptoms from multiple systems
-Recurrent presentation
HIGH INDEX OF SUSPICION
Systemic disease that affects the kidney
-DM
-Vasculitis
=ANCA
=IgA
-SLE
-IE
-Hep C
Diabetic nephropathy presentation
-Diabetic nephropathy is the most common cause of CKD in developed countries.
-In patients with diabetes, there is a steady advance from moderately elevated albuminuria (microalbuminuria) to dipstick-positive proteinuria, in association with evolving hypertension and progressive renal failure.
Investigation of diabetic nephropathy
-Few patients require renal biopsy to establish the diagnosis, but atypical features such as very rapid progression of proteinuria/decline in renal function or the absence of microvascular disease in other organs, including retinopathy, should lead to suspicion that an alternative condition could be present.
-Screening:
=All patients should be screened annually using urinary albumin: creatinine ratio (ACR)
=Should be an early morning specimen
=ACR > 2.5 = microalbuminuria
Management of diabetic nephropathy
-Management with ACE inhibitors and ARBs to slow progression (if urinary ACR of 3+ mg/mmol, no dual therapy)
-SGLT2 inhibitors, reduce cardiovascular mortality and progression of kidney disease at the expense of increased risk of genital infections
-Dietary protein restriction
-Tight glycaemic control
-BP control: aim <130/80 mmHg
-Dyslipidaemia: statins
Examples of renal manifestations of multiple myeloma and pathophysiology
-Cast nephropathy (myeloma kidney)
-Fanconi syndrome
-AL (primary) amyloidosis
-Monoclonal immunoglobulin deposition disease
-Hypercalcaemia (bony metastases)
-In myeloma, a malignant clone of plasma cells produces a paraprotein, often a monoclonal light chain.
-Renal manifestations are dominated by these toxic light chains, which may cause a variety of insults.
Describe cast nephropathy (myeloma kidney)
-AKI, little/no proteinuria
-Light chains combine with Tamm–Horsfall protein precipitating in tubules
Describe Fanconi syndrome (myeloma)
-Aminoaciduria, phosphaturia, glycosuria
-Proximal (type II) RTA
-Proximal tubular injury due to light chain deposition in tubular epithelium
Describe primary amyloidosis (myeloma)
-Proteinuria/nephrotic syndrome
-Renal impairment
-Misfolded light chains (usually lambda) form amyloid, which is deposited in glomeruli
Describe monoclonal immunoglobulin deposition disease
-Proteinuria (may be in nephrotic range)
-Renal impairment
-Usually light chains (frequently kappa) are deposited in glomeruli, causing a nodular glomerulosclerosis
Describe hypercalcaemia (myeloma)
-Thirst, polyuria, bony and abdominal pain, headache
-Bony destruction from metastases
Describe hepatic renal disease
-Severe hepatic dysfunction may cause a haemodynamically mediated type of renal failure, hepatorenal syndrome (HRS)
=vasoactive mediators cause splanchnic vasodilation which in turn reduces the systemic vascular resistance. This results in ‘underfilling’ of the kidneys.
-Patients with chronic liver disease are also predisposed to develop AKI (acute tubular necrosis) in response to relatively minor insults, including bleeding, diuretic therapy and infection.
-IgA nephropathy is more common in patients with chronic liver disease.
-Type 1: rapidly progressive, doubling of serum creatinine to > 221 µmol/L or a halving of the creatinine clearance to less than 20 ml/min over a period of less than 2 weeks, very poor prognosis
-Type 2: Slowly progressive, prognosis poor, but patients may live for longer
Investigation of hepato-renal disease
-Differentiating true HRS from acute tubular necrosis (ATN) can be difficult, but in HRS the urinary sodium is typically low.
-Patients with true HRS are often difficult to treat by dialysis and have a poor prognosis.
Management of hepato-renal disease
-Where treatment is justified – for example, if there is a good chance of recovery or of a liver transplant – slow or continuous renal replacement therapy treatments are less likely to precipitate or exacerbate hepatic encephalopathy.
=ideal treatment is liver transplantation but patients are often too unwell to have surgery and there is a shortage of donors
=vasopressin analogues, for example terlipressin, have a growing evidence base supporting their use. They work by causing vasoconstriction of the splanchnic circulation
=volume expansion with 20% albumin
=transjugular intrahepatic portosystemic shunt
Sarcoidosis in renal
-Sarcoidosis may lead to a granulomatous interstitial nephritis, sometimes presenting acutely, where renal function may improve with glucocorticoid therapy.
-Post-mortem examinations reveal a chronic interstitial nephritis in 15%–30% of patients with sarcoidosis but clinically relevant disease appears to be much less common.
-P: hypercalcaemia: macrophages inside the granulomas cause an increased conversion of vitamin D to its active form (1,25-dihydroxycholecalciferol), erythema nodosum, bilateral hilar lymphadenopathy, swinging fever, polyarthralgia, dyspnoea, non-productive cough, malaise, weight loss, uveitis, lupus pernio, splenomegaly
-I: tissue biopsy, X-ray if lung involvement/ spirometry
-M: steroids
