Chronic Tubulointerstitial Disorder

Chronic Tubulointerstitial Disorders or Ciliopathies is the disease of the cilia of the kidney. The Cillia is a sensor between the tubular cells and tubules. Electrolytes, solids, solutes, and the amount of water are all related to the cells of tubules with the help of cilia with a basal body.

Location of Cilia

It is located in the Proximal convoluted tubule, Distal Tubule, and collecting duct.

Cilia are motile and present in the lungs (some cilia are non-motile)

Embryonic development has cilia. Non-motile is present in the collecting duct and RPE.

Types of chronic Tubulointerstitial disorder

Medullary Sponge Kidney

In this disease, the kidney has a Spongy appearance, restricted to the medulla or the outer part of the cortex. Cause of Medullary Sponge Kidney is a sporadic developmental malformation related to defective cilia. It will measure the solute loss from the body and the water loss. Cystic dilatation of the collecting duct– the greater part of the kidney is affected. A lot of people will know about the disease during an Incidental diagnosis in the 5th to 6th decade(50-60 years old patient) of life with very specific complaints. For the past 2 or 3 consecutive years, the patient has had recurrent stone formation in the kidney. These stones will be Recurrent calcium oxalate. The causes of the stone are urinary tract infection–pyelonephritis, OR tenderness at the costovertebral junction.

Some Characteristic Clinical findings noticed in the patient of pyelonephritis are:

• Recurrent hematuria – stone edges are jagged they cause damage to epithelial walls
• Polyuria– reabsorption of water is not happening as the collecting duct is not able to function properly
• Peritubular cells are responsible for Erythropoietin– cells are damaged, and the production is less
• Causing anemia (severe, moderate, or mild) – tubular diseases of the kidney 
• RTA type 1 - an area proximal to the collecting duct is affected - distal convoluted tubule.

Intravenous pyelography, which shows a paintbrush appearance or bouquet of flowers, is the investigation done for medullary sponge kidneys. A CT scan will show papillary calcification.

The patient's lifespan is equivalent to that of a normal person in India; hence, it is not a dangerous disease of the kidney.

Autosomal Recessive Polycystic Kidney Disease (ARPKD)

In Autosomal recessive polycystic kidney disease, the gene involved is PKHD 1, related to chromosome 6. The protein that is defectively expressed here is fibrocystin/ polyductin. The gross specimen given here is it shows 

• Multiple small cysts
• Radial appearance
• Loss of cortico-medullary differentiation
• The whole of the kidney parenchyma is studded with large cysts filled with degenerated blood.
  • Iron or hemoglobin will break down; hence black
• Left side kidney shows radial striation having medullary cysts

Clinical Features of Autosomal recessive polycystic kidney disease (ARPKD)

• Diagnosed Incidentally in antenatal ultrasound within 24 weeks of gestation 
• Manifestation - ultrasound shows echogenic or enlarged kidney
• Loss of CM differentiation that may or may not is abbreviated by the radiologist
• Oligohydramnios - kidney function defective
• Lung development is also reduced, causing pulmonary hyperplasia
  • Resulting in the neonate age group of death.
• 1-year having renomegaly/hypertension, BP will spike
• ESRD and hypertension lead to death (infant or toddler)

Extrarenal Manifestation of Autosomal recessive polycystic kidney disease (ARPKD) 

• Congenital hepatic periportal fibrosis 
• Portal hypertension can result in esophageal varices. The patient will have vomited blood.
• 1-2-year-old enlarged kidney – the patient has hematemesis(a question can be asked)
• Biliary dysgenesis
• CAROLI cysts

Work-up of Autosomal recessive polycystic kidney disease (ARPKD)

• Ultrasound /CT scan showing echogenic kidneys

Treatment of Autosomal recessive polycystic kidney disease (ARPKD)

• ACE inhibitors for hypertension
• Hyperkalemia – patiromer
• Sodium polystyrene sulfonate (resin)-- associated with chronic necrosis forming enema 
• ESRD- allogeneic kidney transplant

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Autosomal dominant tubulointerstitial kidney disease (ADTKD)

Autosomal dominant Tubulointerstitial disease was formerly known as Medullary cystic kidney disease (MCKD). The genes involved are MCKD 1- MUCIN 1 and MCKD 2- UMOD (uromodulin)

In cases of Nephronophthisis- NPHP 1 which is present on chromosome 2. There are a total 11 types of nephronophthisis.

Frequently Asked Questions:

Q: Where can we see a Paintbrush appearance or bouquet of flowers or Papillary blush appearance can be seen?

Answer: Medullary Sponge Kidney

Q: What is the lifespan of a person with Medullary Sponge Kidney (M.S.K.)?

Answer: Lifespan of the patient is normal in M.S.K.

Q: Where is the gene defect present in Nephronophthisis?

Answer: NPHP 1 gene defect on chromosome 2.

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