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![ Confirm the presence of a normal anion gap metabolic
acidosis
Identify electrolyte abnormalities
Assess renal function
R/o other causes of bicarbonate loss such as diarrhea
Blood anion gap
[Na+] − [Cl− + HCO3−]
<12 = Absence of an anion gap
>20 =Presence of an anion gap
If such an anion gap is found, then R/O other diagnoses
Lactic acidosis
IEM
Toxins](https://image.slidesharecdn.com/rtabikram-160825163722/75/Renal-Tubular-Acidosis-33-2048.jpg)
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Renal Tubular Acidosis
- 1. Presentor- Dr. BikramjitSingh Jafra Moderator- Dr. V.R. Anand Co-Moderator- Dr. Ankit Mangla
- 3. Water andelectrolytes are freely filtered at glomerulus The electrolyte content of ultrafiltrate “At the beginning of the PCT = that of plasma” Tubular reabsorption vs tubular secretion determine the final water content and electrolyte composition of urine Movement of solute in nephron Bulk movement in proximal portions Fine adjustments in distal portions
- 4. Responsible forthe reabsorption of more than 99% of the water and sodium in the ultrafiltrate. 65% of sodium and water is reabsorbed by the proximal tubule 25% by thick ascending limb of Loop of Henle 5% by distal convoluted tubule 2-3% by the cortical collecting tubule Regulate acid-base balance Mineral homeostasis Excretion of organic acids and drugs Has specialized transporters and channels located in the Tubular cell membranes Apical memb. Basolateral side (interstitial side)
- 8. Kidneys contributeto acid–base balance by Reabsorption of filtered HCO3 Excretion of H+ Because loss of filtered HCO3 − is equivalent to addition of H+ to the body, all filtered bicarbonate should be absorbed before dietary H+ can be excreted. Reabs. of filtered bicarbonate 85% in PCT 15% in the distal segments (thick ascending limb and outer medullary collecting tubule)
- 10. The renalacid-base homeostasis may be broadly divided into two processes: 1. Reabsorption of filtered HCO3 In the proximal convoluted tubule 2. Excretion of fixed acids Through the titration of urinary buffers and the excretion of ammonium, which takes place primarily in the distal nephron
- 11. H+ from wateris secreted by the Na+-H+ exchanger on the luminal membrane H+ combines with filtered HCO3- resulting in the formation of H2CO3, which splits into H2O and CO2 in the presence of carbonic anhydrase IV CO2 diffuses freely back into the cell, combines with OH− (from H2O) to form HCO3− in the presence of carbonic anhydrase II, and returns to the systemic circulation via a Na+-HCO3− cotransporter situated at the basolateral membrane of the cell
- 12. In the collectingtubule, H+ is secreted into lumen by H+ATPase HCO3− is returned to the systemic circulation by the HCO3–-Cl− exchanger located on the basolateral membrane The H+ secreted proximally and distally in excess of the filtered HCO3− is excreted in the urine either as titratable acid or as NH4+
- 14. Comprises agp of tubular transport defects charac. by inability to appropriately acidify the urine with resultant met. ac. Normal anion gap (hyperchloremic) metabolic acidosis in the setting of normal or near-normal glomerular filtration rate In contrast, the term “UREMIC ACIDOSIS” is applied to patients with low GFR in whom metabolic acidosis is accompanied by normo- or hypochloremia and an increased plasma anion gap
- 15. Type 1(Distal) Type 2 (Proximal) isolated Multiple/Global tubular dysfunction (Fanconi syn.) Type 3 (Combined) Type 4 (Hyperkalemic)
- 16. Prox tubuledefect Type 2= Bicarbonate reabs defect Loss in urine of Na K HCO3 Cl Uric acid PO4 (Rickets) B’cause distal acidification mech is intact, so H+ is sec in urine pH of urine <5.5 (acidic)
- 18. Primary Sporadic Inherited Inherited renal disease (idiopathic Fanconi) Sporadic (mc), AD,AR X-linked (Dent disease) Inherited syndromes Cystinosis Tyrosinemia type 1 Galactosemia Oculocerebral dystrophy (Lowe syndrome) Wilson disease Hereditary fructose intolerance Secondary Intrinsic renal disease Autoimmune diseases (Sjögren syndrome) Hypokalemic nephropathy Renal transplant rejection Hematologic disease (Myeloma) Drugs Gentamicin Cisplatin Ifosfamide Sodium valproate Heavy metals Lead Cadmium Mercury Organic compounds (Toluene) Nutritional (Kwashiorkor) Hormonal (Primary hyperparathyroidism)
- 19. Charac. byglobal dysfunc. of prox. tub. Glycosuria Phosphaturia Gen. aminoaciduria In addition impaired abs. of Water HCO3- Na K Organic acids Plasma conc of Glucose & aa are within N range, but those of PO4- are low Cystinosis & use of Ifosamide are common causes among children
- 20. Extremely rare,AR Features of both type I and type II (juvenile RTA) Term Type 3 RTA was abandoned as the charac of prox RTA were transient & acidosis was primarily d/t distal acidification defect d/t Inherited carbonic anhydrase II deficiency (k/a Guibaud-Vainsel syn.) CF Osteopetrosis Renal tubular acidosis Cerebral calcification Mental retardation
- 21. Distal tubdefect Type 1= Acid excretion defect B’cause distal tubule defective, so H+ not sec in lumen pH of urine >5.5 Kidney sec K+ in place of H+ l/t hypokalemia As no H+ in lumen to bind to HCO3, so NaHCO3 is lost in urine As HCO3 lost, so kidney reabs. Cl- l/t hyperchloremia Hypercalciuria l/t stone Hypocitraturia Bone buffer (CaCO3) starts to combat chronic acidosis l/t bone disease
- 23. Primary Sporadic Inherited Inherited renal diseases AD/AR AR with early-onset hearing loss AR with later-onset hearing loss Inherited syndromes associated with type I renal tubular acidosis Marfan syndrome Wilson syndrome Ehlers-Danlos syndrome Familial hypercalciuria Secondary Intrinsic renal Interstitial nephritis Pyelonephritis Transplant rejection Sickle cell nephropathy Lupus nephritis Nephrocalcinosis Medullary sponge kidney Urologic Obstructive uropathy Vesicoureteral reflux Cirrhosis Toxins or medications Amphotericin B Lithium Toluene Cisplatin
- 24. RTA +HyperK + Ability to appropriately acidify urine Defect Impaired aldosterone poduction Unresponsiveness to aldosterone Aldosterone Stimulates H+ ATPase Stmulates K+ sec. in exchange for Na reabs by CD Effects Na lost in urine H2O lost in urine K+ not sec. (Hyperkalemia) H+ not sec. (Acidosis)
- 26. Primary Sporadic Genetic Hypoaldosteronism Addison disease Congenital adrenal hyperplasia Pseudohypoaldosteronism (type I or II) Secondary Urologic Obstructive uropathy Intrinsic renal Pyelonephritis Interstitial nephritis Systemic Diabetes mellitus Sickle cell nephropathy Drugs Trimethoprim/sulfamethoxazole Angiotensin-converting enzyme inhibitors Cyclosporine Prolonged heparinization Addison disease
- 28. Pointers towards renaltubulopathy Failure to thrive Delayed physical milestones and weakness Polyuria Polydypsia Resistant rickets (RTA type 2) Unexplained hypertension Constipation Craving for salt & savory foods
- 29. History m/c complain:“mychild is not growing” Other specific complaints include: Polyuria Polydipsia Constipation Episodic weakness Gross hematuria and recurrent UTI’s Seizures and recurrent fevers Antenatal and birth history Polyhydroaminos Premature delivery Family history Similar complaints in siblings, renal stones and hearing impairment
- 30. Physical examination: Generalappearance “dehydrated” or malnourished Weight and height percentiles (often below 5th percentile) Blood pressure Low/normal- exception hypertension (monogenic) such as Liddle’s syndrome will have hypertension (Stage II) Rickets P/A Renal /abdominal mass Ambiguous genitalia/ hyperpigmentation Generalized hypotonia
- 31. 1st step= Completeurine exm. Specific gravity Most children with salt wasting tubulopathy have sp.gr. of <1010 (dilute urine, corresponding to urine osm. of <300 mOsm/kg) Children who can conc. their urine have sp. gr. of >1020 (Renal tubulopathy can be ruled out) Urine pH <5.5 = distal tub. acidification mech. is intact Proteinuria Even 1+ pr. in a dilute urine is significant Glycosuria In abscense of Hypergycemia indicates Fanconi syn Microscopy RBCs & Ca oxalate (as in hypercalciuria)
- 33. Confirm thepresence of a normal anion gap metabolic acidosis Identify electrolyte abnormalities Assess renal function R/o other causes of bicarbonate loss such as diarrhea Blood anion gap [Na+] − [Cl− + HCO3−] <12 = Absence of an anion gap >20 =Presence of an anion gap If such an anion gap is found, then R/O other diagnoses Lactic acidosis IEM Toxins
- 35. Urinary anion gap(uAGAP) (U Na+ + U K+) - U Cl- Normal uAGAP is 0 +/- 5 mΣq/L and reflects the urinary concentration of ammonium In distal acidification defect of dRTA, urinary ammonium excretion is decreased and hence, the uAGAP will be positive In contrast, a negative uAGAP indicates presence of ammonium and an intact distal acidification mechanism as seen with diarrhea (urinary chloride excretion is higher than the sum of sodium and potassium since the increased urinary ammonium in urine has to bind with negatively charged chloride ions to be excreted)
- 37. Spot urine forcalcium and creatinine ratio Assist in evaluation of hypercalciuria in dRTA Some forms of Bartter’s syndrome Dent’s disease Normal ratio is age dependant < 0.8 in infants below 6 months <0.5 in 6 months – 18 months < 0.20 in >18 months age
- 38. Abdominal ultrasonography: Nephrocalcinosis Hydronephrosis Hydroureter Post void residual urine S. magnesium concentration S. PTH assay (for Rickets) Urinary acidification tests
- 40. The mainstayof therapy in all forms of RTA is bicarbonate replacement Patients with pRTA Often require large quantities of bicarbonate, up to 20 mEq/kg/24 hr, in the form of sodium bicarbonate or sodium citrate solution Patients with Fanconi syndrome Usually require phosphate supplementation
- 41. Patients with dRTA Base requirement is generally in the range of 2-4 mEq/kg/24 hr, although patients’ requirements vary Should be monitored for the development of hypercalciuria Pt with symptomatic hypercalciuria (recurrent episodes of gross hematuria), nephrocalcinosis, or nephrolithiasis can require thiazide diuretics to decrease urine calcium excretion Patients with type IV RTA Require chronic treatment for hyperkalemia with sodium potassium exchange resin (Kayexalate)
- 42. Depends onassociated disease Good with therapy Patients with treated isolated proximal or distal RTA generally demonstrate improvement in growth, provided serum bicarbonate levels can be maintained in the normal range. Patients with systemic illness and Fanconi syndrome can have ongoing morbidity
- 43. Nephrocalcinosis, nephrolithiasis(type I) Hypercalciuria (type I) Hypokalemia (type I, type II if given bicarbonate) Hyperkalemia (type IV, some causes of type I) Osteomalacia (type II due to phosphate wasting)
- 47. Children withRT disorders present with polyuria, polydipsia, delayed physical milestones and inadequate growth Detailed h/o along with appropriate investigations can often lead to a specific diagnosis Majority of children can be treated with simple medications Early diagnosis (preferably before 2 years age) can minimize the morbidity and improve growth of these children